I can see where you're coming from, but in my view the general consumer won't put in the effort to exploit your model if you make it appealing enough. I've known people that rented from blockbuster|netflix and just made rips of the VHS|DVDs for their own collection, but it sure wasn't those pirates that destroyed (or is destroying) their business. GOG sells DRM free games and nothing stops me from giving it away to all my friends, but I still end up paying for a new "copy" when I gift one away.
It doesn't need to though, the key thing with the rental business model is it needs to be easy and convenient enough. It's clear that it's a rental in the name, but people will get pissed off if it's not easy to get the content and outlandishly priced, and just go back to BT.