Having had access to
4e for a while now, I must say I'm even less impressed with it then I was when it was announced. I really dislike this game. But, I'm not here to hate on it (indeed, I'm running a tabletop game of it, just to prove that I've tried it).
Despite my dislike for this edition (especially what they've done with Dragonborn and Tieflings) I've stated before it would be very unwise to completely disregard the changes to
4e in terms of setting. This would only isolate new players, and would show a resistance to change (which, in terms of gathering new users and players, is bad).
From what I've gathered however,
4e is completely separate from Greyhawk, so more then likely these races will still not be aloud in that setting (unless disguised). They should be welcomed in the Sigil setting however, but I can't comment on Faerun (simply because I don't care to follow that setting).
So, I gather not much will change (Faerun aside), greyhawk will be as its always been, because
4e never really comes into it from a setting point of view, nor do dragonborn or tieflings - they're just not part of the setting (unless they are disguised, of course). As for Sigil,
4e races will be as welcomed there as much as anything, because it's Sigil, and anything goes. But, thats just what I've managed to gather.
So, conclusively, I imagine ISRP will allow
4e races like tieflings and dragonborns. In the sigil rooms at the least. Not in the Greyhawk rooms I imagine. This is probably a wise course of action: it allows new players to play their
4e characters, but doesn't isolate the oldies who (like myself) don't want to conform to the new edition standards, so rooms like The Crossroads Tavern will stay true to the setting: things with horns just aren't around or common.