Probably won't happen but possible. The problem lies with not the difficulty of making a new map skin, even though it would be time consuming, it instead is with the fact they would have to make sure every single ability of every single skin of every single champion is easily visible on that reskinned map both in regular mode and color blind mode.
You can make the argument" well they shouldn't use it if they are going to complain about something like that I would use it anyways" but that's not how the internet works. The number one post on the boards would be
Riot Fix Your Good Damn Map Skins. They are Trash! We totally can't see pulse fire Ezreals w when he is standing 400 units to the right of pixel brush! Give us refunds a misteryi gift and 200lp now or everyone will quit the game! O and 3 more map skins cause the ones you made I don't like. Those ones should be FREE!!!!!1!