Five years later Russia is still going to be a giant on clay feet. Economic growth and throwing money at the army, are
not going to solve the glaring structural deficiencies that caused Russia's failures in WW1. Especially because prior to WW1 no side realized the weaknesses that plagued Russia.
Massive Russian armament is going to spark massive military investments in Germany and A-H.
Franz Ferdinand probably would use his three (assuming F-J still dies in 1916) on the throne to unfuck the common army a little bit. We would likely see (at least) a massive influx of money, to train a proper number of draftees. So in case of war A-H is likely to perform slightly better than IOTL.
With Germany not going for Schlieffen, the Entente is in
big trouble.
Tsarist Russia won't be able to fix its faulty military structures in 5 years. 5 more years of massive spending are going to improve performance sure but take a minute to think about the German reaction. Also lets not forget that a lot of Russian money is going to flow into the navy.
Instead of a single army with second-rate troops, Germany is likely to field several armies with first-rate troops in the East. Five years are
not enough to mitigate this, Russia is very likely facing a much bigger disaster than IOTL.
The plan to concentrate on a knockout blow against A-H only makes sense ITTL, if Russia is able to field more armies. Otherwise the 3-4 armies the German Empire likely fields will draw away strength from the A-H front.
I see three likely scenarios here:
1) Russia, surpremly confident in itself, decides to go on the offensive against Germany and A-H.
Needless to say that this is bound to have disastrous results for the Entente. Sure, A-H is going to bleed but there is no way that Russia has enough strength to pull off a successfull offensive on two fronts.
The offensive against Eastern Prussia is likely going to end in a disaster on the scale of Tannenberg or worse.
Best case is a quick end of the offensive in Galicia and a massive redeployment against Germany, to plug the gaps.
Worst case would be a disastrous defeat in Poland or Eastern Prussia but inter-army rivalries and mission creep prevent the redeployment of much needed reinforcments from Galicia.
2) Russia, confident in its new strength, decides to focus the initial offensive on Germany. The plan is a "combined" (expect similar cooperation like IOTL) French-Russian offensive to quickly overwhelm Germany.
Best case for the Entente in this scenario, is an Eastern repeat of the Frontier Battles.(
https://en.m.wikipedia.org/wiki/Battle_of_the_Frontiers)
Worst case is a scenario similar to OTLs Tannenberg, possibly on a larger scale, but Germany has the reserves to exploit their success.
3) Offensive against A-H and defense against Germany.
Here Russia would be able to extract a higher price from any German relief offensive and A-H is likely in bad shape for the rest of the war.
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In the West France is likely to impale itself on stable German defenses. No "Rape of Belgium" has massive repercussions for mobilization and propaganda, especially in Britain.
I don't think the Central Powers would be worse of ITTL. Quite the opposite. Germany made two massive strategic mistakes ITTL. Attacking Belgium and unrestricted submarine warfare. At least one of these mistakes is butterflied away here.