Three views on this-
1: As far as the YZ universe goes, there was a bit on that timeline (somewhere in the ARG stuff, not hunting for it right now) that one of the major events was the country's first female president (Clinton, anyone?) being convicted of treason, which led to the abandonment of free elections and the religious right seizing indefinite control. IMO that was intentionally left vague (e.g., what act of treason?), but indicated that there was some thought put into the idea of the GOP losing in 08 and how to get the storyline to compensate. So it wouldn't be difficult to warp the history of the immediate future around the Obama victory and end up in the same place (assassination, treason, terrorist attack in DC, etc., there's hundreds of ways to do this). Speaking of warping future events, I could suggest a War-of-the-Worlds-style hoax at the upcoming Academy Awards to relaunch the ARG, but that might be a little too much to take for folks who aren't in on the joke
2: As far as the TV show, this is what worries me. Sure, the show can go ahead just fine story-wise, but I personally don't see HBO picking it up. Fingers crossed that I'm wrong about this, but it seems like it's a great idea that's about two years too late. Two years ago, they were facing the end of their big flagship series (Sopranos), and science fiction/fantasy shows like BSG, Lost, and Heroes were runaway hits. Not to mention that under a Bush admin YZ was very topical. Now we're at a point where Lost has become more of a cult phenomenon than a mainstream hit, BSG is ending, and Americans are trying to look ahead at the positives instead of counting the minutes until the whole craphouse goes up in flames. So I see HBO execs thinking that YZ is a great idea, but one that simply goes in the pile with all the other great ideas and doesn't stay at the top due to lack of marketability. I figure that if they were going ahead the earliest they could air it would be this summer, at which point the science fiction programming trend has lost its shine and fears of a country run by neocons and religious nutters is dated news compared to what we'll be dealing with (and, frankly, if it isn't we will have much bigger problems to worry about than what's on TV). Just going by the numbers, it's likely to tank in ratings because in that environment it'll be a hard sell for the network.
3: Which leads me to the actual album. I don't think there's any reason to be concerned for the storyline, a writer will write whatever the hell they want to write and the rest of the world be damned. Especially when the person writing the story is looking at it from the end and just has to chart a way to get there. The question IMO becomes will Trent feel as compelled to release it if there's no show and/or ARG. This is where his leaving Interscope becomes a truly wonderful thing, because for the reasons I listed in 2 I think they'd tell him to shelve the idea like they did with Ghosts on the assumption that it wouldn't sell. Whether it'll make gobs of cash in the Top 40 is, thankfully, no longer the point. Whether Trent feels it's compelling enough to work on, instead of something else that he finds equally compelling, is. That one is something only he can answer.
Though I really hope that he does do it as I thought YZ was the best work he's ever done. I don't know if it'd do billions of dollars of sales (I kinda don't know if ANY album can do billions of dollars of sales these days, but that's a different wall of text), but I do think there are a whole lot of people out here in the wastelands who care very much and want to hear this album.