I don't think Sonos is the right candidate. Their system is based on their own speakers and their connection software. That gives them a lot of control over the system, but limits their ability to work with other products.
Linkplay might be a better fit. They have a broader offering and their Wiim products are not as proprietary as Sonos. With Wiim they have a pretty good reputation in the audio market. Wiim users common use LMS which is an open source system, but not nearly as flexible as MC. MC would also add video capability. And, since they support streaming services, it would will a gap that MC has struggled with. The question with them is whether they want to expand into a system as complicated as MC.