I am probably being stupid
You are proposing that a company forfeits 15$ of profit in the licensing division in order to generate a lesser profit (if any) in its phone division. On top of that if Nokia will actually do that it can be (and will be) immediately accused by all the usual suspects of selling under "cost" and dragged in front of every single competition authority under the sun.
Nokia making phones makes sense both in terms of leveraging its brand (so easily disposed off by MSFT) and financing more R&D to ensure that those 15$ stay there from new patents when the old ones expire.
While at it, the 1Bn loss by Sony is not what what is says on the tin. All of their devices now reuse software developed for the mobile division. It does not matter what you buy - a TV, a BR or a stereo it will be running Android and it will be running the same media player with the same bug for bug compatibility (which pretty much proves it is the same software):
1. Failure to parse ID3v2 version 4
2. Identical bug-for-bug behavior on video codecs
3. Identical bug-for-bug behavior on progressive jpegs.
So actually, the 1Bn losing mobile division of said manufacturer is financing the development of the whole range of consumer electronics :)
I suggest you analyze the use case for both of them in depth a bit further :) You missed quite a few of the income (and expense) streams.