It's good that Ford is ditching Sync... but what killed Sync was Ford not Microsoft. Sync is a forked version of Windows CE that is maintained by Ford (and offshored to a 3rd party vendor for maintenance).
The bugs, the poor UX, it's all a result of extremely poor execution on the part of Ford. Switching to a new OS doesn't solve that problem.
Poor execution is still possible, but it's now easier to execute it well.
A very real example I witnessed many times: Bob the Product Manager has an idea. He calls the contractors in Germany who own the embedded Sync code to tell them this idea and they take it as a spec requirement. They write the APIs exactly the way the PM thought aloud. The PM then tells the in-house Ford team who supports the code after its written this idea and they freak out because it completely breaks the semantics of the API. German folks didn't care because they get paid more and they need to keep their customer happy, the PM. Ford engineers care but don't have much power to fix the solution other than one off hacks to get the software done in time to meet the vehicle launch date. Customers suffer. Ever wonder why if you enter the Bluetooth menu from the phone vs from a media stream it actually does two completely different things? Or the fact that iPhone requires you're connected over the Apple cord and protocol but actually streams over Bluetooth and weird edge cases ensue? All caused by this style of execution.