Quick reply...

I am not sure. I have not used that much Linux.

However, I am thinking that you should be looking at:

1. number of Linux users, by distro (CentOS, Ubuntu, Debian, Gentoo, Fedora, whatever);

2. radical changes made in these distros lately (systemd, polypaudio, moving-to-cloud, default-browser, GUI);

3. relationships between these two.

It might be that there are more people and-or corporations using Linux instead-of-or-alongside Windows, and thus more people are using Linux, for one reason or another. It may cause quakes in Linux community, because people with radically different mindset and habits arrive.

Or maybe, Linux distros are reaching stage of "maturity" when they are too large to innovate, and instead they switch to uniform systemd-and-polypaudio.

Or maybe, Linux feels that some new innovation is needed, to keep it from getting tangled in continuous mess of maintaining distros similar to each other, and compatible with their past.

Best wishes.