Since it's a largely hypothetical scenario, I'll state a couple of assumptions I made in saying yes:-
We don't pay for
bug fixes now, nor should we ever. (Note, just because you don't like something, doesn't make it a bug)
The content we would receive would start to take big chunks out of the 'Suggestions' forum on GTP.
But, people always want something for nothing, or more for less. So it's bound to meet with a lot of resistance as a suggestion.
I don't think though it's a viable proposition for all games. With GT it's easy to add content with very little imagination.. new cars and tracks are all out there - PD just has to make a virtual counterpart. Great though GTA games are, I wouldn't pay a subscription for them, because they'll run out of new things much sooner, how much more can they really add? Once PD ironed out the bugs, then added in features we want, then started piling in content, GT would be just about perfect. And say the subscription was $10, and only 100,000 people ever signed up, that's $1,000,000 a month on top of usual sales - surely that would go some way to speeding up the process of generating content.
edit:
What's "WHAT WE ASK" and what are "OUR SUGGESTIONS" anyway? The things that you may like, other people may not like it.
I think there is a bit too much obsession with the community suggestions and stuff. Let PD do the job, its their work.
If you go to the suggestions forum you can see how easy it would be for PD to please a lot of people, maybe not everybody, but that will
never happen. I can understand what you are saying if people are asking for machine gun power-ups and teleport pads - but the top suggestions people are voting for fall very much inside the Gran Turismo series remit.