This is the most concerning part to me. The hardware appears to be done and Particle provides a great quality and price on nRF52 boards. I can understand dropping backend support for the hardware. I haven't yet seen a good argument for stopping manufacturing.
As a company that creates hardware I think it's important that people know that hardware will be available when replacements are needed. I appreciate that you've open-sourced the design files and am hopeful someone creates a xenon-clone. I'd much rather buy from Particle though.
If I was looking for hardware to run a new project on I'd have to take in to consideration that Particle boards may not be available when I need them.