There are Challenges
In the event that Bush does win a second term, it is very hard to imagine Cheney running for the presidency after Bush. Sure, he COULD run, but there would be a Republican primary season - he would not automatically be the one to be the republican nominee.
In this case, though, I think that the usual mode of politics don't apply because what we're moving toward is a shadow government - in fact, we already have one.
Bush is a figure head, the front man. Cheney & Co are the power brokers, the string pullers, the policy forumlaters. They will stay behind the scenes. If it comes to it, they will find another figure head to run ..... hmmmm, let's see, there's a governor down in the state of Florida that comes to mind .... Jeb Bush.
Or, and here's where my cynical despairing brain takes hold, try this scenario. Bush wins re-election. Then, in the summer of 2008 before the subsequent elections, there is a massive terrorist attack in the US, Bush & Company dissolve Congress, declare a state of emergency, abrogate the constitution, and cancel the election.
Once I would have laughed this off as ludicrous. Not anymore.