Hussar
Legend
Hussar! Throwing the first edition war bomb!
If 4E meets expectations, there will be no reason to go to 5E soon.
If 4E fails to meet expectations, there will be reason not to invest in a new edition.
With no true setting support to keep fans of previous settings or to inspire people new to the game, it may cripple the long-term viability of the line. The 3 and done model for settings will, IMO, prove to be incredibly short-sighted.
Having said that, again IMO, any prospective 5e isn't likely going to be done by WotC. I truly don't see them doing it unless the 4e line collapses utterly and they reverse design direction on a great many things. But if that happened, I would expect Hasbro to simply shut down the RPG division and hold onto the IP.
The first one? Really? 4e is going to tank so badly that Hasbro would rather keep D&D on the shelf than do 5e with WOTC? I guess that's just speculation, rather than edition bombing.