We'll I am good enough on making prediction and I think that the current configuration is good enough and it can handle it for a couple of years .. But I must also consider that I've never had a Mac and I don't know enough about it .. My main concern was the problems of the dGPU with the 2011/2012 models and the power of the iGPU ... As I said I have a very old PC which has only an ati Radeon hd 4650, so I'm a newbie of iGPU/dGPU
You're right to be concerned about the dGPU failures.
2008 - NVIDIAgate (but then, it affected every other manufacturer who used the 8600GT).
2010 - NVIDIAgate v2 (GT 330M in the 2010 15"/17" MBPs)
2011 - Radeongate (Radeon 6xx0M cards used in Sandy Bridge iMacs and MBPs)
2012 -
possible NVIDIAgate v3 (GT 650M cards in Ivy Bridge 15" rMBPs).
I got bummed by Radeongate. That said, I put the blame on AMD for making thermally-inefficient chips, Apple for putting such a card inside a cMBP chassis in which the thermal design is already bad enough, and the factory workers/robots for not applying thermal paste properly.
When I replaced it with a late-2013 15" rMBP, I opted for a dGPU, because:
1. The NVIDIA chips are far more power efficient.
2. The rMBP has a far better thermal design and ventilation.
Even with the dGPU activated, it runs at a pretty cool 50ºC.