New POSIX OSes won't take off in a meaningful way either (whatever 'meaningful' means). It's nothing to do with it being POSIX or not, it's just difficult to get traction for a new OS. Linux faced exactly the same issue when it was released.

But why do you need it to take off in a meaningful way? Open Source software doesn't need a particular market share to keep going, it just needs a certain absolute number of people (which differs depending on the software). Is having a small committed core of users not enough for you? If your research is truly useful then that number will grow over time.

Unless you're talking about a commercial OS, in which case Microsoft is your obstacle, not POSIX. Good luck with that.

Maybe, maybe not. IMO, capabilities-based systems are all around us these days, just not in a completely pure form and not in the way most people expected (it's at a higher level, that is, in the way apps are being built on web APIs).

I also note that Microsoft built a capabilities-based OS (Singularity - it's open source, have you considered building on something like this?) and that one of the most important modern contributors to the space (J. Shapiro) now works at MS Research last I read. Given his lifetime interest and work in the area it's not a stretch to imagine what they may have hired him to work on.