Anyone saying downloads will be too slow or they can't be arsed waiting for a game to download, go and download WoW.
https://signup.worldofwarcraft.com/trial/freetrial.htmlIt starts downloading while you pop your details in, by the time you're finished entering them you can start playing, let's bear in mind that WoW is pretty much the biggest game ever too.
There's no reason 90% of games couldn't do this and any new release could be downloaded prior to launch and just unlocked on release day.
Personally I think they'll probably both launch with a Blu-Ray equipped machine with a terabyte HDD or bigger, all games will be available on disk or download at first, after about a year they'll both release a AAA title as download only, they'll force people to use the download service, and then disk releases will start to dry up. They'll have the DL games about £10 cheaper than the boxed ones too.
You can all say it'll never happen if you want, but this will happen next gen, I guarantee it. There's just no reason why they wouldn't do it, the extra money they'll make from cutting out retail coupled with the destruction of the pre-owned market would far outweigh the lost sales from people who don't have broadband.
I suppose for those people without decent internet they could put vending machines in high street retailers that you plug your HDD into and it installs the game to it.
The benefits to the format holders, publishers and developers far outweigh the negatives.
As for Nintendo, they'll probably keep with the disk based games, they're always a bit behind with this sort of stuff and in honesty their audience would probably be scared off by having to enter their bank details into the internet.