Yes, it will probably still work. To get an idea of the future, I'd look at the past.
From the software side:
MacBook Pros from 2007 got upgraded to Mavericks. Assuming that's the last OS X update they will get and the next version of OS X is planned for 2014, they will have gotten 7 years of eligibility for the latest version of OS X. Staying one version behind for an extra year would have pretty much no negative impact. Even staying 2-3 versions behind is not really a big deal (there are lots of Snow Leopard users still). Assuming that trend continues, you should be all good in terms of software compatibility.
From the hardware side:
Let's look at a high-end MBP from 7 years ago. (I'm not choosing 8 years otherwise I would have to do a PowerPC vs Intel comparison).
Processor: Intel Core 2 Duo 2.33GHz
RAM: 2GB DDR2-667
GPU: ATI Mobility Radeon X1600 256MB
Hard drive: 120GB 5400RPM
Note that this is the basic config for the high-end model (not ultimate), I'm not sure whether there were BTO options for an even higher-end config back then.
Those specs are pretty weak by today's standards, but still entirely useable for basic everyday stuff.
Here's a "review" of a 2006 MacBook Pro done last year to see how bearable a now 7-year-old Mac is:
http://www.youtube.com/watch?v=H7auHMcHkvs
Of course expect to spend on a couple things at some point like a new battery, or a replacement charger.