I am not definitely against bringing back the league system however I don't like the way this proposal deal with it.
For example if you decide to play in bronze league but get reward cards over this limit than every card above the league limit is useless (if I don't count the small amount of glint you can get back by burning).
Another point is: Why a player with a max-level-deck cannot decide to play in more than one league in this case ? This would do IMO sense as benefit for his investment.
Maybe the most important point is that it does make the way for a new player who is ready to invest a large amount of money harder. Now he can buy a max-level-deck and beat (nearly) all opponents in bronze, with this proposal he would need to decide if he want play in bronze where he cannot use the advantage of his max-level-deck or if he play in diamond / champion where he probably get beaten by more experienced player.
Mayve I overread it but I could not see that this proposal say something about diamond / champion - this was in the "old" system two leagues with the same cap (max) - should this stay or what would be the plan ?