.. The point of the original post was to lobby for support of the F3 platform in the hope that demand might build. ...
You are not alone.
This week I received a F3 Nucleo with the Motor controller shield. While I needed to place a Mouser order for some more directly needed items, I could not resist the $35.00USD price on the dev kit. While I was most interested in the motor and the shield board. The Nucleo is a F302R8.
At least I have access to the HALMX code that allows for quickly lashing up a simple project. I downloaded the support files which claim to include a plugin for the CubeMx tool. A lot of the docs and tutorial refer back to the $1100.00USD motor kit. The rest relate to setting up the IAR tool chain.
I made it as far as generating the .ioc file. Then went back to the work on hand. While I could have run through the blink and serial I/O sketches that work on my other Nucleo boards. I am pretty much 100% that this board would work the same.
In skimming through the downloaded docs, I notice that the Shield should work with other Nucleo boards. I think the F103 board was included.
I got out my other Nucleos, such as the F401 that I sometimes work with and the F103 nucleo. They are all the same PCB board. Even the silk screen and the revision number is the same. The sticker differs which is probably how they differentiate the products. I also notice that all these boards use the same 'R" package. Which probably simplifies things. That way Pin X is always function Y.
I am now of the feeling that support, is something that one has no control over. Demand on the other hand is purely determined by the lowest price of he shiniest object. I do not think the two are related.