I'd have to disagree that Netflix is killing Gog's movies, for me what's killing it is still DVDs. I have absolutely no desire to watch a film on a phone or to tie up my computer when I could just put a DVD in its player and watch on my TV. DVDs are much cheaper too, I can get most things for £3 or less, no internet dependancy and I can resell the copy as I wish.
Digital media is inherently inferior to having a physical copy unless it can:
Act as a cloud (for me, irrelevant as mentioned above)
Be much cheaper (Gog's software titles on sale are much cheaper than on disc)
>Offer something unique/unusual
The main problem I'm seeing at the moment is everyone in the wishlist requesting /awesome/ films that are available everywhere, that everyone's already seen. Bring me something obscure that I can't get for myself and maybe you'll have a sale.
As for the service dying out - is it actually costing anything extra to run it? If not, it won't die, unless it becomes embarrassing.