That commit does not drop 32 bit support, rather it drops 386 processor specific code. i386 is not gone yet. The multiarch kernel supports both i386 and x86_64. Debian Wheezy which will come out in 2013 still has a 32 bit version, I just installed it 2 weeks ago in a VM for some other app that was 32 bit only and didn't know how to link in the multiarch libs.
32-bit will still be supported (x86_64/AMD64/x64/Intel64 support 32-bit via legacy mode).
HOWEVER, with the rise in requirements for games on other platforms (Planetside 2, anyone?) and the jump-over from Windows is anticipated, going 64-bit within a year would be great.
I stand corrected.
(Since I already had this written out...)
i386 was the Oldest of the 32-bit CPU types that was supported, being the first 32-bit x86 CPU. i486 and up are still supported, including as MrSchism mentioned, the 32-bit support on 64-bit processors. (And of course non-x86 platforms such as arm can be 32-bit)
However, of course Steam should treat 64-bit games as first-class citizens (if they are not already) on a 64-bit OS
When will Valve make us a 64 bit steamcmd for gods sake?
Nothing extracted yet.
https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=743aa456c1834f76982af44e8b71d1a0b2a82e21
i586 support is older, so assume that would be going as well. Also, when configuring 3.8rc1 and linux-next I'm not seeing any options for 32-bit support.
Given this, you can expect ubuntu to likely have a kernel which drops 32 bit support in late April, and a guarantee for late October. Most large and easy linux distro's will follow a similar timeline. Faster moving distro's, like arch and gentoo, will have it within 1.5 months.
This should be a matter of a simple recompile and a few bug fixes, but get on this!