Hmmm. What specific X-risks are you worried about? UFAI beating MUFAI (what I consider this to be) to the punch?
Not sure about 'probably destruction' and no life going to arise in universe (Hubble volume? Does it matter?). But I think that the choice is unrealistic given the possibility of making another, less terrible AI in another few years.
-A lot of this probably depends on my views on the Singularity and the like: I have never had particularly a high estimation of either the promise or the peril of FOOMing AI.
-Hubble volume? Really? I mean, we are possibly the only technological civilization of our level within the galaxy, but the Hubble Volume is really, really big. (~10E10 galaxies?) And it goes temporally, as well.
Hubble volume
It matters. There's a good chance our universe is infinite, but there's also a good chance it's physically impossible to escape the (shrinking, effectively) hubble volume, superintelligence or not.
I'm inclined to think that if there was intelligence in there we'd probably see it, though. UFAI is a highly probable way for our civilization to end, but it won't stop the offspring from spreading. Yes, it's really big, but I expect UFAI to spread at ~lightspeed.
X-risks
UFAI's the big one, but there are a couple others. Biotech-powered script ...
I offer this particular scenario because it seems conceivable that with no possible competition between people, it would be possible to avoid doing interpersonal utility comparison, which could make Mostly Friendly AI (MFAI) easier. I don't think this is likely or even worthy of serious consideration, but it might make some of the discussion questions easier to swallow.
1. Value is fragile. But is Eliezer right in thinking that if we get just one piece wrong the whole endeavor is worthless? (Edit: Thanks to Lukeprog for pointing out that this question completely misrepresents EY's position. Error deliberately preserved for educational purposes.)
2. Is the above scenario better or worse than the destruction of all earth-originating intelligence? (This is the same as question 1.)
3. Are there other values (besides affecting-the-real-world) that you would be willing to trade off?
4. Are there other values that, if we traded them off, might make MFAI much easier?
5. If the answers to 3 and 4 overlap, how do we decide which direction to pursue?