Or the iTunes Digital Copy.
I will download the video exactly once. It then lives on my computer, and I can copy it onto my iPod or iPad.
That is convenient but I think it is still the wrong question.
Eventually, the first download-only (no DVD) will be released by a studio. Then a second. The studios want download-only because then they control everything. You will never own anything from them again.
Then the studios demand further restrictions from the hardware manufacturers. Abandon old format A and include new format B.
Sure, you can repurchase all your A content and they'll even give you a discount on the B versions. But they will set the A price at whatever they want. What choice will you have? Stay with your old electronics and disable the updates?
No matter how convenient they make it it is still about removing your ownership of what you've paid for.