I live in Singapore and this is already happening here. In Singapore to own a car you've to get a certificate of ownership that can cost around $70-$100k and you've to bid for this. Ever since Uber began to get popular here we've had rental companies (who only rent if you become an Uber driver, essentially partners of Uber) try to undermine the bidding system by artificially boosting prices.
It has never been easy (or cheap) to privately own a car in Singapore but the situation right now is exactly like you mentioned in your comment.
However I'm also a resident of the US and I don't think it's gonna happen over there anytime soon.
I have lived in both the states and in Singapore (current). I've taken approximately the same amount of Ubers as you but it's also because its prohibitively expensive to own a car here. For the benefit of others: it can cost upwards of $100k to own a car, and that's for a cheap ass car and you've a maximum tenure of 10 years on that.
I've to agree with you on the other points however, traditional cab companies have shitty drivers who would mostly refuse to take you to your destination. Grab car drivers are usually rude (relatively) and unpleasant to deal with. I seriously wonder why this is so, in an island as small as ours and with both companies marketing to the same pool of potential drivers.
It has never been easy (or cheap) to privately own a car in Singapore but the situation right now is exactly like you mentioned in your comment.
However I'm also a resident of the US and I don't think it's gonna happen over there anytime soon.