Are you sure you have to be logged in to PSN to play the game? I don't see why that would be necessary. There's a lot of online functionality, but I don't see why you couldn't play offline.
The download time will be a pain, but Sony lets you resume downloads even if you turn the PS3 off in the middle of the download and come back later. I mean, they could put the game up at midnight on launch day, and you could just let the download run overnight so you could play it that night when you get home. Sony could also build infrastructure to handle stuff like this; for example, they could have you download some sort of load-balancing client that would queue your download so as not to overload their servers.
This is definitely the way the industry is heading, slowly but surely. I can't see GameStop liking this trend one bit; in fact, it wouldn't surprise me if they ultimately introduce a digital download service for PS3 games once digital distribution reaches critical mass. The catch is, Sony already has their own servers that can do the job without needed to give GameStop a cut.
But yeah, the fact that you won't be able to share games with your friends is lame, but Sony doesn't care about that. Now, hopefully they'll give us a price break on digitally-distributed games, but that hasn't been the case so far.