You are right. From what i know, GTX770M and above (MXM module) can be switched, not sure GTX765M is soldered or MXM.
For CPU, intel I7 or I5 should be more than enough. Unless some gamers prefer high/ultra setting then they may opt to I7 (online, multiplayer, cpu intensive games)
For budget tight "normal person need", I think they have no choice, bcs most of the laptop are with CPU and GPU soldered especially GPU. Future upgrade is unlikely. Lenovo Y500/Y510P is exceptional.
If <RM3k, the most can go is I7 + GT750M or AMD GPU
If RM3k~RM4k, the most will be I7 + GT750M/GT755M SLI or GTX765M
For compatible issue, this one cant avoid, expecially every year when there are new GPUs released. Next year is more extreme: GTX880M with 8GB!! not sure is 28nm or 20nm.
Hmm.. depends on what kind of games TS plays..
Most games I've seen stresses on the GPU much more than anything else. I'm still using first generation i7 and it's working fine.. what's killing me always is having to upgrade my graphics card.. has changed from GTX 275 > 275 SLi > 580 > 580 SLi > 780.... -.-
I would say as long as you have an i5 dual, you should be alright and try to opt for better graphics... correct me if i'm wrong.