Ok, so it's a $400 mp3 player that can be replaced by a $40 64GB usb flash drive as far as sync is concerned.
Nothing is ever guaranteed as far as future support for obsolete hardware, especially one that has so little market share.
It's ok to be disappointed but there are plenty of options that are orders of magnitude cheaper than getting rid of the vehicle.
There is no 'ground' to stand on or principle (not principal) at stake here. There is some compatibility issue with the new software that apparently only affects Zune and Ford isn't going to spend any resources to fix it. Better get used to that because nobody else is going to continue to support it going forward either - probably including Windows.
What are you going to do if you buy a new vehicle and get a software update and that car no longer supports Zune? Get a USB drive or 2 for the car or get a new mp3 player. Or get rid of the Edge and throw more money down the drain. Your choice.