Neat TL, I can't wait to see how things develop. Rather disappointed you didn't put up
this video in the OP though (warning: political content may be offensive to some)...
Some musing on the development of the ground war:
The Iranians are not the Iraqis or any other Arab armies. They have a number of defects inherent to being a rather dictatorial and politicized armed forces but they are nowhere near as mindbogglingly incompetent as the Iraqis. Most of their soldiers actually do know how to shoot with some degree of accuracy, how to maneuver, and how to use their kits more advanced features like infrared scopes and fire control systems. They do train realistically, sometimes, and they can be fairly inventive with some use of tactical initiative. They may not be as good on a man-for-man basis as any Western or major Eastern military power (like Russia and China), but they are still leagues above the opponents the US has faced in previous Middle Eastern wars. Basically, their decent soldiers. Not great, not bad. But decent.
On the operational-strategic level, after watching both invasion of Iraq, the Iranians switched to a more realistic style of guerrilla warfare, with layers of irregular fighters, backed by trained commandos, and fast moving armored and helimobile battlegroups, all under the cover of hit-and-run aerial ambushes. The Iranian-trained Hezbollah demonstrated some of Iran's tactics in Lebanon in 2006 with good success, so we know the Iranians were (and are) on the right track. Their response to any American ground invasion will be to (at first) trade-space-for-time so as to ensure US forces become logistically overstretched (the longer distance from the Iraqi border to Tehran means it's impossible to make a single it in a single lunge like we did in going from Kuwait to Baghdad). Specially trained and prepared "stay behind" guerilla groups based around the IRGC, Pasdaran, and other paramilitaries will emerge to attack American supply lines once major combat forces have passed by. These will be coordinated withhit-and-run counter-attacks by the aforementioned mobile battlegroups so as to maximize both of their effectiveness. The Iranians will invariably balance the aggressiveness of these assaults with the need for force preservation, so as to deny the US a decisive battle that would accelerate the conventional phase of the conflict.
The Iranians are not under any delusion that they can win against an American invasion, but they do hope to delay, string it out, and cause enough casualties that the war becomes politically unpopular and the Americans will ultimately call it quits. And they have laid the full ground work for a insurgent movement so they could continue to implement a assymetric strategy when (note: not if, when) the US were successfully occupies the entire country.
TL;DR: Expect a longer and bloodier conventional ground campaign then experienced against Iraq in either 1991 or 2003 followed by an insurgency that makes Iraq and Afghanistan looks like child's play.
Also:
Bush was giving a speech in Georgia, the former Soviet republic. The grenade also killed Georgian President Mikhail Saakashvili, who was closer to the grenade and suffered even more severe injuries than President Bush. It is unclear whether the assassin intended to kill both men.
While you've laid the ground work for an invasion of Iran, you've also prevented Georgia from getting curbstomped by the Russian's in '08. Silver lining!
Iran would take a helluva beating doing this though, since the attackers would lose the element of surprise as soon as they fired, or indeed as soon as they came within missile range of the carrier task force, if they were in civilian craft then they would be warned away and then sunk if they did not turn back. I'd estimate 78% casualties on the Iranian side for 10-20% on the US side.
Modest nitpick here, most of the anti-ship missile attacks on the Hormuz would undoubtedly be carried out by batteries of mobile launchers operating on and around the Iranian coast, not by Iranian naval vessels. I imagine most of those would be used as mine layers (another handy, cheap weapon for closing the straits) and being conserved as a "threat-in-being".
In both cases, the US would have to take pro-active measures to inflict casualties on the Iranians. Although, as both the 1991 and 2003 "scud hunts" show, finding and hitting mobile launchers can be
really hard. Probably the only way the US can be sure to stop the missile attacks would be to physically secure the coastline with troops.
