4. A lot of this is because the OP is vague--how "modernised" (which for simplicity's sake let's say Japan at best, Siam at minimum) should Persia be. From what I know, I think Russian levels of modernisation are doable from an early enough POD, later Ottoman levels of modernisation. Yes, Afghanistan is a mess (I remember a college lecture where the professor showed a map of US/US allies control vs Taliban control, and it isn't what the media would want you to believe, that's for sure). Mountainous terrain is difficult but not insurmountable for state building. All that's needed pre-20th century is for the people to nominally accept the rule of the Persian ruler, and at most provide minimal tribute and maybe some soldiers when needed. Any real incorporation of the Pashtuns can wait till later.
Does it help them modernise? Not much. But the increased population dwarfs the historic rivals in the Ottomans, and is just under half that of Tsarist Russia, who can't project that power well thanks to the rough terrain along the hypothetical Persian border. And since this is relevant to any further argument--what would you have as Persian borders? I think I mentioned my vision earlier, even if control on the ground isn't always there (like occurs many times when discussion borders in pre-modern non-western countries, case in point the borders you will see for states in Southeast Asia and Africa). But population isn't everything, but it is providing a wide labour pool for any industrialism.
10. Maybe. Here again is the issue with the OP--to what extent? Late 19th century China could probably kick around anyone besides the two great powers they neighboured for reasons more than just numbers. And I'm still not convinced you would have an ethnicity based civil war compared to a religious one--Hinduism (that cultural Indian faith) could be the glue that forms a united country. That's bad--but once again we go back to comparing who is worse, and I will still say the British. With India (and the central Indian state the Mughals) having a more sane demographic growth (not stunted by famines that got blown far out of proportion because of poor British policy) and not being economically mutilated by British policies (the economic stats do not lie since they seem like they more than adjust for difficulties in determining things back that far), you could have the base of a country that is at least Siam-tier, which when you get the Mughal state's population, that's a very significant economic base. The issue--were the Mughals capable of doing this modernisation? It would take a lot of uprooting the indigenous states (drawing on Siam, that would mean a centralisation of the state). It would need to be a lengthy process. There's the issue the Mughals could be swept aside by a society like the Maratha (who bring similar issues) or even someone else.
11. Empires end because of the actions of individuals and the forces of society they mobilise, on either side. There is no physical law that says an empire can't last forever, it just needs to be that the forces it mobilises can defeat those that threaten them most to preserve some semblance of an empire--as I said, any evidence seems circumstancial based on the situation of the time. For the Turks, the most obvious of these threats is Russia, but the threat of internal nationalism is perhaps just as great. It didn't help that external forces (Russia, again) loved to support that threat of internal nationalism. There could have been a person able to mobilise the forces of reform and modernity that existed within the Ottoman state to keep the Ottoman Empire relevent. There were people like this in the Ottoman Empire OTL, and there perhaps were equally brilliant individuals like a Sergei Witte waiting to be found and given a high position who never were discovered thus their names are essentially forgotten.
They were, but they were known for carrying swords often (a status symbol, granted) and this was the era when Japanese martial arts fluorished. Edo Japan seems like a society that if needed could re-militarise quickly.
4. I feel my point is rested, you are just talking about some grand potential Iran, with Nader Shah as its ruler or his varied sons as its ruler, how this situation avoids the rise of Ahmad Durrani, the Durran-I-Durrani, idk, who was created from the Afsharids essentially.
A good Iran base would be Iran and Iraq, it provides just enough to do well and not enough to be a problem. This is achieved by Is'mail defeating Sulayman at Chalidran. However, I need not go into details, you have already agreed the Safavids are better. In all honesty, you and any would agree that having Iran inside Afghanistan isn't the greatest policy, it's like saying well America needs Mexico or Guatemala. Would America have more industry or population with these lands? Of course, but it is draining and wasteful and not the easy way to significant westernization of Iran, it is a net detriment.
10. We have divulged into semantics and the water has been muddied to the point, that I do not understand what we are taking about anymore.
11. Ok, I will give a more long drawn and detailed response...
1. You are correct, a political entity essentially can last forever, look to the Roman example which survived in many different styles through the ages. However, that is a different thing than a single royal dynasty to rule unfettered through an unprecedented length of time when faced with multiple heavy hitting political foes. Notice we have the Ottomans facing over the generations extremely varied opponents and forces, some of which they overcame and others that they, do to the turn of time and fault not of their own, can never defeat decisively and surely. The list can stack to the ceiling, but to start with some:
-The Mamluk powers of Egypt formed the first major threat, but in the form of an alliance early on and later with a war. Ottoman's engaged with Burji powers as upstarts and relatively outmatched in terms of cultural achievement and at one point, technological prowess. The fact the Ottomans, a tiny tribal entity, would rise to defeat the greatest state in Islam at the time, is, and would be, ASB had I said it in relation to any other power; it was truly extraordinary.
- The Timurids, the most dangerous of Ottoman rivals. Timur the great, defeated Bayezid and crushed the Ottoman Empire under foot. Such a defeat and loss would seem to be the doom of the state. Yet, in a way, that can only be labeled ASB, the Ottomans revived and outlasted the Timurid giant to its east. Much more, conquering Constantinople, surpassing the Umayyads in glory.
- The Safavids, as if arising out of nowhere and born of the saga of continual dominant generals and fantastical rulers of the east, Shah Is'mail conquered Iran and claiming to be a deity defeated the vaunted Muhammad Shaybani. Despite being one of the most gifted individuals in Islamic history, Is'mail, with a larger force, was defeated by Sulayman and forced out of Erzurum. Such a victory is truly auspicious, as the Ottomans, put to shame the last of its true Islamic competitors, the spiritual descendant of the Timurid entity.
This is a short list, but you see the initial point. The Ottomans were perhaps the luckiest and most effective royal courts and states in human history. They defeated Europeans and Islamic foes alike, the world over bowed to them. However....
Ottoman power in the early stages with and without weakness bested opponents through a mixture of effective rule and superior resources and manpower, these would be those mentioned and Poland-Lithuania, Venice, Hungary, etc... They are in the future faced with opponents on all sides and from all angles, that it cannot simply overpower in the same way, who are near intrinsically against them and their interest.
The rise of western imperialism and the colonial boom, was something the Ottomans could never predict not prevent, the enlightenment changed the landscape. Europe was on the move, in ways the Islamic world never imagined, the Europeand buzzed with ideas, not of practicality but of theoretical views, and abstract thought. The creation thus was the individual above the collective, such a thought is foreign to the Islamic world, but with it, started the first catalyst for the growth of things and innovations unparalleled in Human history. The Ottomans will miss out on this revolution no matter the changes, even if one goes to 1230, the result is the same, Ottomans lose out on the innovation.
Right off the bat, this puts Ottoman power behind the West, and is going to be out maneuvered and circumvented completely, making them essentially economically obsolete and in terms of navy irrelevant. Never before has the Ottomans faced such a insurmountable disadvantage. Then on top of this, we have more opponents to deal with....
The age old enemy Austria still looms. Which the Ottomans ever increasingly cannot engage directly whilst being one circumvented and dealing with Russis at the same time, not to mention it had issues in Iran, Iraq, Nejd and Egypt. Austria will inevitably outpace the Ottomand in significance in Hungary, Serbia, Croatia, Romania, etc... Just by the geological threads tugging on the Ottoman state, which are stressing it to the point of collapse.
Then the most dangerous of them all, Russia. While you say, oh well Russia was backwards and of course Ottomans can outpace them in technology, etc... This may be true, but what difference does it make? Russia posses a natural advantage over the Ottomans in terms of manpower, resources, fighting spirit, logistics, etc... The Russians losses further, a near homogenous empire, of immense size, something the Ottomans never faced, especially while also healing with Austria and the West, with falling economic importance and naval prowess, which is declining at no fault of their own.
To further add, look at the history of Ottoman-Russian relations. Initially, Ottomans held the upper hand and Russia needed vast allies to overcome the Ottomans effective rule and stunning array. But overtime, effectiveness only becomes so essential when put to the test of incalculable economic growth and endless resources. Thus, as Ottoman power declined, again due to external circumstances, Russian power over them steadily increased, as Ottoman effectiveness proved unable and will near always prove unable to cope with unlimited resources and united countrymen, especially when also engaging with other powers and dealing with acute overextension.
One cannot blame the Ottomans for joining WW1, which spelled its execution, what other choice have they? To wait, and allow Russia to win and be completely swallowed or become a puppet of the British? No, they had to join, it was the only way to save their dynasty and recover some advantage over Russia, which had been chipped away by the tide of endless Russian resource and fervency. If they do not join, then what happens? Swallowed by an emboldened and fattened Tsarist Russia and imperialist UK or consumed by the flood of revolution as it engages in a Cold War with the coming USSR.
The Ottomans despite their grandeur and exceptionalism, simply cannot weather this storm that is likely too much for any state we know of to overcome in its situation. In my opinion it did better than one would ever expect it to have done. As well, going down in WW1, was more fitting for it, than the alternative of a emasculating end at the hands of nationalist rebels in the era of fascists and communist revolutionaries.