sounds good for some kind of games. for example i just want tp play the battlefield 3 multi-player and i only want to play bioshock single.player.
so selling the whole game as retail and only the multi player as download is a good first step. next step would be to get the opinion to buy only the single-player as well. no clue how they will handle that but i think there will be a way in the future and if i have to pay less then i will be happy as long as both experiences together won't cost more because of that.
they could make it like:
full retail version like before 60€ or so
or
download only single or multi.player and pay less for one of the modes but both together can cost little bit more than the 60€ version (or 60 as well and they make still more money because there's no retail for that). no customer would have a disavantage then but the developer can still get a decent amount for the game and doesn't have to fear that they will make much less money then and the customer can get only what he wants for less than the price nowadays.
if i would have had the chance to pay xx% less for battlefiled 3 without single player i would have done it and if i would have had the chance to get a bioshock single player only for xx% less as the full game price i would be happy with that (depends how much xx would be^^)
they even could say: both versions (only single or multiplayer) cost 40€ each (for example) but if you have bought one, you can get the other for 20€. then you can still get the full game for the same prcie than retail and the develper won't get much less if he only sells one part.
(these are all just fast examples from me. sure the numbers don't make so much sense because a download should cost less than retail and so on but it's just to say how they could do it. i think this would be good for everyone)
