If gog.com went away tomorrow, downloaded games and installers should be copyable to another PC relatively easily (so far this has worked 100% for me at least).
I'm not sure how easy it will be to copy downloaded games to another PS3 once Sony pulls the plug on the PSN store (and likely PSN login) for PS3 next year.
I’ve run into several games that will not launch at all of you don’t have galaxy or galaxy has no internet.