sure, why not both or all three
Nokia seems bound to not understand the market it is in. Or, it's own business.
If you are going to focus upon hardware you are going to be much better off going with the flow when it comes to software. That may mean a MeeGo table. Or, it might be an Android tablet. Or, even a Microsoft tablet.
Choosing just one is far too limiting.
You can go strickly proprietary as has Apple. But, even HP is likely to not focus so strongly on WebOS that it ignores other operating systems.
Not picking Android because it does not want to be an "also ran Android" is silly. You still have to compete with them regardless. That is the huge mistake that Nokia has already made in regard to focusing only on the Microsoft phone. Coming out with a MS phone does not protect Nokia against the Android phones. They are still competitors regardless of whether or not Nokia makes one. Or, two or three.
What is Nokia's business? If it is to make the best handsets, then you do so for all prominent software systems. Why restrict yourself? If you did not have the staff to make software work it might make sense. Or, as in the past, if you had and applied only your own software, it might make sense. Apple takes that route.
But, if you only make the hardware, it is stupid to restrict yourself to only one OS. Even if it is a good choice. And right now, Microsoft is not up to par. And it may never be. Microsoft has to compete against the likes of Google, Apple and even RIM. Adding the Nokia set does not change that.
Funny how some in the industry think they are better off by offer less choice. Less choice than is already out there for the consumer.