In light of recent acquisitions, new CEO and inclination towards IoT, Cypress needs to re-evaluate their stance on Windows only treatment to PSoC creator.
The locked-in clients might be happy with the existing offerings. But given the current stage of IoT, the early adopters, hackers and innovators would rather go with something that provides deterministic and cleaner workflow instead of click and drag approach of PSoC creator. Blink a LED should be as easy as plug board the board and run a script (see arduino, rpi).
May be publish a simple plain text DSL for UDB configuration and release a binary that would do all routing and assembly of ARM and UDB components. I think PSoC is itself using GCC for ARM part. IDE could be second thought.
With 4.0 there is a project makefile export. So you could do the hardware part on Windows (maybe a VM) and the do the software part on Linux using a GCC installation. (I did never test that, but I should). I'm not sure how good the debugging with e.g. OpenOCD or JLink works on Linux, though.