I have to say I am opposed to term limits,
all term limits, but in particular the Presidential one. I do think it automatically sets up a second term President as an ignorable lame duck.
But since "the second term curse" existed long before that little beauty was enacted, it can hardly be faulted. (Darn it.)
Right now Bush's two biggest problems are Iraq and energy.
Iraq won't be decided in his favor or against till long after he's gone -- so his actual legacy and place in history is on hold till then. Short term that works against him because people only care about the here and now, which is discontentful and tired of hearing death statistics.
Energy is a similar no win in that virtually nothing he does is going to help
right now. Without that relief, his poll #'s don't significantly improve. Even though his long-term moves may well prove him some kind of energy genius, as with Iraq, it's dim for the immediate future. At least energy prices have a shot at stabilizing before his term is up, but I'd guess the damage will have been done.
(I do think there are things that can be done, but as watchdog commented, it ain't going to happen.)
(Ironically the "scandals" of the past week helped the President by drawing attention away from what should have been the most politically damaging event: 2000 dead American soldiers in Iraq. No amount of diverted media attention is going to get people not to pay attention to their hurting pocketbooks, though.)
So, by my estimation, his two biggest problems don't go away during his Presidency. Popularity/Job Satisfaction stays down. And with those sagging numbers come Bush's real problems.
A) Rats deserting the ship. Nobody likes to back a loser. (See Ms. Meirs.)

Republicans trying to position themselves as decisive leaders for the next presidential election. Method of choice? Saying an unpopular President is full of it and here's how it
should be done. (The "1000 planners but no doers" conundrum.)
See, the problem isn't the obstructionist, loud mouthed Left, but the opportunistic, full of itself Right. The ostensible head of the party can't control the party he heads.
What does Bush need to do? A) Cut energy costs.

Boost the economy. C) Find a way to address Iraq to the American people's (no matter how begrudging) satisfaction, something all the "stay the course" rhetoric in the world isn't going to accomplish. (I swear this administration is horrendous at propaganda. It's as if they think right makes might -- that being right is all they need. It isn't.)
If he can do that his numbers recover somewhat (he needs them at least in the 50's -- even if
only 50) then he can address his party by saying, "You want to be President? You need me. Get on board or you're screwed, numb nuts." Right now he just doesn't have the clout to pull that off.