I don't think there should be any cap. Whore the fuck out of both of them if you want.
My condition would be that you can not have two players in the same draft year. That's a bit silly imo. Maybe even make it a mandatory gap of 2 seasons, but 1 might suffice.
Otherwise, I actually don't see why we shouldn't implement this for S50. Or S51 I guess for timing purposes and because that's actually the start of the next half-century. If all the potential issues do end up being true, we can can it by S60.