Fairly sure from what I heard last year that there are no long term plans for S1156 as a platform for new processors. Didn't stop me buying one though, as in well over 10 years of upgrading I've never bought a cpu without also buying a mobo anyway.
My attitude is, if you are waiting a couple of years between upgrades, the chances are that by the time you do, technology will have moved on and simply slapping a new cpu in, even if available, will leave your system lacking in other areas, whether that be chipset performance, memory support, mobo 'features' etc etc. Not always but 'future proofing' is more something for serial upgraders who are constantly changing their system to think about.
1998: Celeron 300a on Slot1
2000: P3-650E on s370
2002: P4-1.6A on s478
2004: Secondhand 3000+ on s754, only did it because it was cheap, probably a silly move in hindsight, sold it for a small loss the next year
2005: Venice 3000+ on s939
2007: C2D E4300 on s775
2009: i5-750 on s1156
^Those sockets were either pretty much dead by the time I upgraded, or would have left me with something not really up to scratch. Yeah, so maybe I could have dropped a quad on the s775 platform, but it would still have been well off the pace of a 4.2ghz i5 which wasn't too expensive given the MSI mobo launch deals (also nforce 650i chipset wasn't the best for clocking quads).