The thing is though the Prem teams would be able to find enough players through their worldwide scouting networks, they no longer need to rely on poaching talent from other clubs.
Basically the Premiership has 500 players but prior to this ban on relegation presumably they will be cutting it down a bit to 16/18 teams like UEFA want, so 400-450 players. Half of those players will be superstars bought in from wherever meaning we'd probably need at most 250 extra players to fill the void, these clubs will find them somewhere. The draw of the Premiership will be sufficient, and I don't think it would completely kill grass roots football, I mean realistically how many lower league clubs in England think they have a genuine chance of playing in the Premiership in the short-medium term without spending huge amounts of money, probably no more than 50 I'd imagine. These clubs will still be around still training up kids, if anything one could make an argument to suggest that you'd get even MORE young players brought through in the lower leagues because these clubs will have to resort to training up youngsters rather than flashing their cash around in the lower league, parachute payments, rich benefactors trying to bankroll a run into the Prem.
Not suggesting I think we should get rid of relegation but I certainly wouldn't think the Premiership clubs would have any trouble whatsoever in filling a squad of 25 players, with the guarenteed income they can just wave wads of notes at people and bring them over.