While we are speculating, consider this:
There are several people (Joe Wilson comes to mind) who warned the administration that there wasn't evidence of Sadam possessing WMDs and that was "before" Bush made is case for war. That, if true, would be the "biggie" IMO.
And with all the bribery and shady dealings throughout this administration (Delay,Abramoff, Cunningham, to mention only a few), who's to say it doesn't go higher???
As far as Cheney goes, and I know most don't follow this, so I'll make it brief, it is suspected that he is the other "un-named" leaker in the Plame investigation. A couple weeks ago the administration after two years,turned over more than 150 e-mails to Patrick Fitzgerald that they originally had claimed were "lost" through whatever process. However, I read that Fitzgerald had conviscated Cheney's computer in the beginning, so it's possible other info was revealed.
Not only that, both Cheney & Bush did testify directly to Fitzgerald, but neither of them under oath.

It's suspected that Cheney will be called to testify again, this time under oath. If he has something to hide,or if he was involved in any of this, he'll step down.
Sure, we are speculating on "what ifs", but there are so many secrets and shady dealing charges here that you have to ask questions.
All that being said, unless there is a major breakthrough of some kind, or unless there is more outrage by the public to pursue some of these issues, I think it won't be until after Bush is out of office before we know the full truth.
TIS