I was impressed with the keynote but I question how well they can execute all this. I also question developer interest. Yes all this makes developing for Windows easier but many devs are simply biased against Windows.
Only time will tell, but ms seems to be taking all the right steps.
Addressing win8 shortcomings for desktop users and enterprise lures them to upgrade, as does the free update offer.
By making metro apps more capable and better at interacting with the desktop (they run windowed and support expected features like drag and drop), they make these apps compelling for the huge user base to consume/buy them.
And by making them universal all platforms benefit from the huge user base of windows, and attract developers as well as they can target more devices with little cost/time.
And finally, by using bridges developers now can take their existing project and have a windows presence, which is useful as a temporary solution until windows gets a buying user base that warrants a freshly developed app.
I can see it having no effect, but I must say, I'm very impressed so far. That and the platform itself being so tightly integrated on many devices sounds like it's going to be an amazing as hell ecosystem.