The really interesting prediction in that article is that there will be two smartphones sold for every one PC. Since today's consumers tend to show more fanboy/fangirl behavior about their phone rather than their PC, people who focus on traditional systems rather than mobile risk alienating 66% of the potential user base.
As for WP7: at present it's easy to calculate that >20000% app revenue growth is needed to come near iPhone. Even android's >800% app revenue growth is amazing, so surely not even the "Nokia" magic word makes such huge growth seem likely. People who scoff at revenues from Android apps might like to think about that.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
