I'm pretty sure they'll reconsider the final strategy if this device is successful. At least it seems to get pretty much positive attention right now.
It's a shame, without the useless Intel deal this phone could probably have hit the market last summer and could actually have had a real shot at changing things. Now it's dead in the water. After wasting my time for months on the N900, I'm not going to touch again a dead platform.
If this is successful -- which I imagine will depend on which carriers run it and how they push it -- I think you'd see a strategy to converge the experience somewhat so there could be a natural successor to this phone.
If they are as tightly wound as it seems, it could come in the form of changes to WP7 (tho of course that application grid would have to go!).
But what's far more likely I think is a layer not unlike HTC Sense. That would be a brilliant little way to bring people on over to a strange and foreign land of WP7. And many many people i'm sure wouldn't even realize that the underlying platform is different: If their web browser, calendar, social feeds, etc, are the same, then it looks just like an upgrade.