No way, in 2 years they will only stop shipping new Intel Macs but will continue supporting existing ones for a few years more.

Last PowerPC Macs were released in October 2005 and first Intel-only MacOS X was released in August 2009, almost 4 years later.

That's what happened last time:

Intel support was announced during OS X Tiger, and 10.4.4 was the first public release with support for x86. 10.7.0 was the first release without support for PPC. So 10.5 Leopard and 10.6 Snow Leopard were the two major releases with support for both Intel and PPC.

Now, Apple tends to provide security updates for at least a few years for each OS release, so I can envision recent Intel Macs getting security updates for another 4-5 years.

Up until last month I would've said they would keep things around much longer - I mean, they supported old iPods and iPhones far longer than their competitors...

But the killing of openGL and 32-bit software is making me wonder about their previously-amazing commitment to supporting older things.

I suspect that killing 32bit was a necessary step, as they aren’t going to port deprecated features to new platforms.

They did some of this before intel, I think with some of the transitional MacOS->OS X APIs.