Microsoft should have run a transition. Yes back away from the release of devices, but state for the record something is yet to come. This would have a double message to the O.E.M. and the Windows Phone community.
You show you are pulling away from the manufacture, but you also keep an already panic riddled community calm.
You don't even have to give away fully what will be your one and only future phone, just a press release with a view of a kickstand, or something that is Surface related.
I am very sure they have been in talks with Samsung who may take a lead roll with a device that will dual boot ( WC Story ), and even with as much as I hate Android...a Galaxy Note that can boot into Windows 10 for Mobile would catch a great many people who would otherwise just wait out a Surface Phone. I am also very sure Microsoft eased up on the transfer fee Samsung must pay to sell phones, if they bring Windows 10 for mobile into the mix.
Microsoft needs to do one better then Apple and tease something. Heck they already have an almost perfect stage in which to do it any of the NFL broadcasts....a simple 10 second spot with something in shadow....and one word "Soon" or something like that.
They have to start the buzz.....
Heck if I was head of Marketing I would hire David Attenborough to voice very cryptic spots and start the world talking, have him talk about how humans learned to communicate, how things evolve over time..... then at what ever event just hearing that voice smooth chill the words Microsoft Surface Phone would be like a verbal orgasm to the Windows faithful.