Fairly good I would imagine... There were so many of those Beyliks that it would have taken just one crafty leader to capitalize on the situation.
Though there are alternatives... The lack of a strong Turk state might prompt the Il-Khanate to expand it's borders, instead of keeping the Turks around as tribute states, though if Osman was killed, then I'd imagine the Seljuks would retain power for atleast a little while longer, and things would have been the status quote. Either way, the walls of Byzantium are going to fall to the Turks, whatever their ruling family may be.