Exactly how we've been doing with gMail, Docs, Music, Movies and Photos.
Cool, but what about G+, Wave, Allo, Songza, Glass, Reader, Ara, etc, etc.
Google's killed more high profile projects than they've kept. I'm really hesitant to invest my money, or advise people to invest their money and time in any cloud platform.
Keeping your 'metadata' isn't a great answer, if this tanks you get to buy the game somewhere else and import your save? yaaaaaay