Right now I'm not seeing a solution outside of season rentals to properly address the various loopholes and also push the benefits towards card ownership. Different forms of exploiter also seem to be pretty commonplace. If people want to try out cards for a lower price, they could try to rent them in the last few days of the season or persuade a guildy to delegate a card to try it out. They could also consider buying and selling cards too.
Season rentals also align markets and demand for cross-game mode usage: ranked, survival, land, tournaments & brawls. The one loser is people specifically renting wild cards for brawls, who play ranked in Modern, but value could be obtained via tournaments.