These would be my current predictions and thoughts:
.com
Will always remain the very best.
.net
Will continue to do well for community/networking/education websites.
.org and
.info
Feel we (as domainers) should stay away from .org completely and leave that name space to non-profit organizations for ethical reasons. Wish we would also be careful with registering .info's for the same reason.
.us, .in, .cn ('real' ccTLDs)
Major country code extensions like .us and .in will do well in the years to come. I actually feel that these country codes should also be left to the citizens of the respective countries, although I have sinned with a few premium .in names myself
.cc, .tv, .sc ('generic' ccTLDs)
.cc will continue to do well for premium names as a catchy and memorable alternative to .com.
.tv will do well for premium names that are suitable as television brands.
I don't see any future worthy of mention for .sc except for premium single word domains.
.eu
Will do ok with things 'European' like politics and travel, but the extension will never enjoy the advantages of a real country code or a generic TLD.
.biz
Can't think of .biz as a good investment, but the extension will probably still be around for a while.
.mobi
I don't see much future for this extension beyond a two year horizon at all, despite what many other people (including major investors) are apparently thinking. To me the extension sounds/looks extremely awkward, and not cool at all! Besides, everything will be mobile within the next few years anyway, so I'm not sure who would want to refer to the concept of mobility with their domains in 2 or 3 years time?!
After processing all of this, and working with a 3 to 5 year horizon, I'd put them in the following order (while leaving out .org):
1. com
2. net
3. cc, tv
4. info, us, in
5. eu, cn
6. biz, mobi
7. sc