Actually this proposal isn't charging anyone to play there is no charge to play in modern league. In regards to owning older cards there are still a couple of uses for them renting them out or using them on land. In fact I could see botters placing enough cards up for rent to pay for thier season passes. This would actuallly help the conomy of the game without kicking the botters out.
I play wild and feel that my position is waaayyy to high so a bit more competitive decks to play against would be nice. And yes I feel that this will do that as bot farms will want to increase the power of thier bots so that they can earn enough to cover costs. Unless they do the renting out as described above.