I disagree with changing rentals. We've already made a huge impact 10xing the rental cost of many cards.
I don't even consider this an exploit or a bug. It's a feature. It's part of the strategy. There are benefits to owning, other benefits to renting long term and other to renting for 2 days, take a break and rent again later. When card prices go up, it's good to be a owner, which isn't what's happening for the most part for the past 3 years. When card prices go down it's better to rent. If you find a good deal it's better to rent long term or if you don't want to keep looking for cards to rent. If you want to spend an extra effort to improve the efficiency, it's better to use that tactic.
However, I would support a change that would make rentals tied to seasons. The problem with my idea is that it would require a lot dev time (I imagine) not only on rentals but also on other things. My idea would be to have every single rent last until the end of the current season, no matter how much time left (you could auto renew for more seasons). Player A puts up 2 cards for 10 DEC for rent. Player B rents it at the start of the season and pays 10 DEC for 15 days. Player C rents it at the end of the season and pays 10 DEC for 1 day. Cards could only be used by 1 account per season. It could even work well with survival mode, but I would have that cards on cooldown would get back to playable for the next season, even if they had cooldown left.
Other changes that would be needed for this to work properly would be to have tournaments and brawls star and finish during the same season.
Given all of these difficulties, I can't see it being implemented for a long time. Since my vision for these truly seasonal rentals is not possible for now, I prefer things stay the same.