How futureproof is the top-end 15" MacBook Pro?

I'm not particularly well-versed in processor/GPU specifications, so I'd like to get some advice before springing for the top-end MacBook Pro which costs a limb and a half.

I've had a 2007 MacBook Pro with the X1600 graphics card which I quickly traded in for an early 2008 MacBook Pro with 8600M graphics, which was in hindsight was a pretty good choice for this machine has lasted me more than 5 years, even playing Dota 2 at a rather decent frame rate which I doubt the anaemic X1600 is capable of.

I think the processor should be pretty okay (correct me if I'm wrong), and I don't think the upgrade in clockspeed is worth the money so I'm leaving it at 2.3GHz. What I'm concerned is if the GT 750M is decent enough to last at least another 4-5 years, especially given that it has to power a high resolution display.

I've done some research and it seems like the 750M isn't much of a jump from the previous 650M, but at the same time, it seems that Apple is phasing out discrete GPUs for integrated solutions so I'm not really sure if I should thus get this model before it happens.

I'm not a heavy gamer; most probably would be using this machine for casual gaming like Dota 2 and light to moderate video/photo editing.

Basically, I'd like to get opinions more learned than mine whether this would be more of a X1600 situation where Apple shipped a rather abysmal GPU, or 8600M which actually lasted a pretty decent number of years.

Thanks in advance.