1 will never happen, and 2 will probably only affect a small percentage of cars, like in GT5 you couldn't sell the 1million+ cr cars.
If they made it the way you've said, then no-one would have any credits, people would stop playing and PD would not make any money, because people would boycott them.
GTA V has micro-transactions also for in-game credits, but the payout system in GTA online is terrible, anyway, nothing like GT, and at least in GTA people have been glitching their way to 100s of millions anyway and boycotting the stupid micro-transcations that way.