IMO the pro-elop camp never showed any business strategy or management knowledge. With my very limited knowledge of what is going on at nokia I would say "wp7 only" is the wrong decision. Very risky (wp7 not exactly a success), destroying brand value (loyality to windows not nokia), damaging the Qt ecosystem (which they should push hard) and too much dependence on MS.

But I don't know what else is going on at nokia, maybe they'll have s40 with swipe UI ready in a few months, or some really disruptive meego tech ahead, or will offer plenty of services (not only maps) on all wp7 phones or w8 tablets.

Those are big IFs, so until proven wrong the wp7 strategy is a mistake.