I wouldn't worry too much about professional applications as there will be interoperability between Avlalon and Windows Forms.  Just because it's written in Avalon doesn't mean it HAS to look unique, it could still use all the standard windows forms controls and regular windows.

However, I agree that there will be a slew of lower-budget, smaller applications that will make me want to barf when I see them.  At the same time, with a good, creative designer on the team there could also be a slew of lower-budget, smaller applications that will amaze me with their visuals and intuitive interfaces.