After eight months of work, SDL 2.0.9 is finally released!
This one has a ton of bug fixes, plus some new fun things. This is still API and ABI compatible with previous SDL2 releases, so everyone should upgrade. If you are on macOS 10.14 ("Mojave") you should absolutely upgrade right now to get OpenGL working again.
You can see the official announcement for the big picture and download links.
Now that 2.0.9 has shipped, the batching renderer has been merged into mainline, as have Wayland server-side decoration support for KDE (explained in this video over here).
The next steps for me on SDL are going to be merging all this into the Nintendo Switch port, improve the Wayland target a little more, and maaaaaybe port it to another game console!
Enjoy!