I am an owner, therefore I much appreciate making managing the rental options easier. As things stand I usually do not touch a card once listed as it is just too much effort.
I have a little over 200 cards up for rent over two accounts and this will probably be the amount going into the new system as well.
If however things become as easy as you describe and still stay as profitable as they are today, I may(!) consider quitting active play entirely and rent out my whole deck with something around 1300 cards in the future.