Once the Experimental branch is the default then, yes, it will house the official servers. After that, how long will they continue to support Legacy?
Right now the current version (which we might as well start calling Legacy now, since it will never again be updated) is already down to just a few official servers. They’ve been quietly killing them off over the last few months.
Per May 23 Devblog:
The ‘default’ version on Steam right now isn’t being updated. We’re rebooting. The version I’m posting about in these updates is on Steam under ‘experimental’. We post updates every day.
When will the reboot be default?
When there’s more people playing reboot than default we’ll make it the default. We’ll put the reboot on another
archive branch so you can keep playing it if you want to.
When will that be?
A while away. While we are making real serious progress in the reboot… and we think it looks and performs better – not all the gameplay elements are in yet. We’re missing major features like AI and building. We don’t expect anyone to play it properly until those are in.
Why are you doing this? Why not just update the default?
After a few months of trying to update default and failing to update at the rate people wanted, we decided this was the way forward. The old code is very limiting in pretty much every way possible. When we originally released on Steam we expected to get a few loyal players, to update regularly and to tidy the code up as we went along. Now that 1.6 million people have bought the game we feel we need to make things happen a bit faster than that. And this is happening. Everything you see on the experimental branch has been made from scratch in the last few months."