With the money they poured into Nokia and the amount of support they're throwing behind HTC, it would be hard to think they'd have anything to offer outside of a more attractive look to match the Surface devices.
Plus, if they want to make sales they need to announce these before the WP8 hardware hits the streets.
The only reason it would happen is the same reason Surface tablets are coming out... they'd have to be really sick of OEMs screwing up. I don't see any evidence of that on the smartphone platform right now. In fact, all of them are stepping up their game this year.
It might actually be a good idea if they go after a market that the OEMs aren't, a direct competitor to iPhone in terms of size and power. The 4" super phone that the OEMs must think nobody wants.
I actually wouldn't mind if they made a WP8 iPod Touch equivalent though, honestly
Intel has its own motherboards for sale. Not sure how this is any different. Surface phone is the look I want, not a softened rectangle like the HTCs or the much larger 920. I could handle a 920 if it was no thicker than my Titan. I want a big screen in as small a size as possible. My Titan for example is nearly perfect. Nice hard lines in the style. Nice classy finish color and feel.
If MS did want to design a phone then why wouldn't they just give the design to another OEM to make it for them like how Google does with their Nexus products?