The GOP must be kicking themselves. With the current state of the economy, Obama is vulnerable to a credible candidate. As much as they try, the only credible candidate running is Romney, and republican voters hate him.
Any number of Republicans waiting until 2016 could have made a more interesting challenge
As it is, Obama will face a token challenge from Republicans
Bullshit. Obama is suffering disenchantment even from some of his most ardent followers. He is vulnerable period! But keep believing what you want, it'll just make the job that much easier to unseat the failure in 2012.
The problem facing the GOP is the problem the Democrats faced in 2004 and the problem they themselves faced in 1996. You have a vulnerable President, but your best potential candidates for one reason or another decide to sit it out. And just like in 2004 and 1996, you won't win at the top of the ticket just by being "Not Obama." You can't pick up moderates or independents without some kind of plan and you can't get any cross over votes without something that they can latch on to.
I still think Romney can win, but most of the rest of the field? Not so much.
I also think you're making a dangerous mistake in underestimating Obama in campaign mode. Clinton, Bush, and Obama were all dangerously weak thanks to some horrible first terms, and yet Clinton and Bush won. Part of that was a weak opponent, but the other part is that they, like Obama, were INCREDIBLY strong on the campaign trail. Not only that, but if the GOP picks someone too far to the Right Obama's base will shore up incredibly fast.
I won't predict an Obama win yet, but in about 3 months if the candidate isn't Romney... yeah, you can call it. Obama will win.