Given Naughty Dog's pedigree with Uncharted 2's single player & multiplayer, I am not worried for a second about this.
I hope it's not competitive multiplayer though. I love it most of the time - don't get me wrong, but I honestly prefer co-op modes in the vein of Left 4 Dead, Resistance 2 etc. Dedicated stories that follow the same basic structure but differ on repeat playthroughs. I think they work really, really well and I think they'd be perfect for TLOU.
With God of War jumping on the competitive multiplayer bandwagon, though, I guess it's probably likely to be forced on this as well.







