Based on the SpringRTS game engine, which itself started off by getting Total Annihilation into 3D, Beyond All Reason is going to be a standalone free RTS and it's coming along nicely.
The developers announced recently how they've been hacking away at the old Spring engine, to bring the performance up to modern standards. Some of what they've added in includes a whole new multithreaded pathing system, along with moving to modern OpenGL4 rendering. The result is impressive with better performance, and support for thousands more units and buildings in a single game.
A small showcase video was also put up:
Hard to say, because core spring dev is not too active these days and the changes in this fork are huge. We tried to get through with a smaller PR few months ago but reviewing took too long for it to be relevant.
There is a possibility it will just become the new main Spring version, but time will tell.
As for when they expect Beyond All Reason to see a proper release:
We are aiming for mid 2022 with Steam release though the game is kind of fully playable and even now.
From now on we are going to mostly add content like a sp campaign and improve lobby experience.
In a more recent video they showed off thousands of units on a map with plenty battling and it does look pretty spectacular overall: