I do agree with both of you. I was thinking about the release of Windows 8 and the years ahead. The way I see it there is just a matter of time before ARM is being pushed into both desktop PC's and, more importantly, notebooks. Better performing chips and a lower price than what Intel and, of course, AMD can deliver should make these interesting for normal consumers.
x86 is relevant today but in five years? I'm not so sure about that.
I think an ARM based laptop/desktop will be able to do what most people use a PC for. Google and Apple are rumored to be moving their mobile OS upwards towards the laptop/desktop and NVIDIA is working on a full ARM based CPU.
x86 has peaked and will see it's market shrink. Granted even if they lost half of their market in 5 years they would still be fine.
x86 will be around for a long time and so will PC gaming. Just not on the scale we see today.