This is one of the reasons that I hope Metro apps crash and burn - if the only way to get hold of them is through the MS store, with all the same issues that the Apple store has, then I just don't want anything to do with them. I know that the Android equivalent has problems (piracy, for instance), but I'd rather have that than something completely locked down.
I can't imagine how MS would save face if Metro crashed and burned. Seems like it would be tantamount to checking out of the consumer market.
And seeing as Windows is not and never was an OS for power users, they will lose the remaining desktop niche - which will be populated by exactly those power users - as well once the tablet will be our primary multimedia communication device.