I know we've talked about this before, but I'd like to see a grass Masters added to the mix, probably Halle, and then turn one of the hard court Masters into an ATP 500. It is a small change, but it would both make "grass season" more meaningful and also add another faster big title.
I don't think it will happen anytime in the near future. First of all, we should remember that until a few years ago, we did not even have ATP 500 on grass and the entire grass season consisted of two weeks (the week right after RG and the week right before Wimby - neither of which is a good choice for top players).
The first problem would be which one should be 1000 - Halle or Queens. Queens apparently does not have good facilities, but has great tradition. Halle has good facilities. but it was founded only in 1993. So, I think it will be a difficult choice. So, the administrators decided to call it a tie and made both 500s instead of creating 1000.
The second problem is that if there is a grass 1000, then in that week there should not be any other tourney. That would mean ATP would need to find a spot to move the other tourney. The other tourney would neither like to be in the week after RG nor would like to be in the week before Wimby and there is no other spot in the grass season.
So, the only solution would be to extend the grass season by one more week. Since Wimbledon already shifted their tourney dates, they cannot do it again. So, RG should be moved ahead by a week and this would mean they have to cut the clay season by a week, which is actually doable.
But, don't expect anything to happen for the next 10 years at least.