Developers are definitely working on Multires! And yes I will update the video when it’s available to us.
Unfortunately there’s no viable alternative to multires and it really stressed me out when they removed it in 2.81. Multires is an old sculpting method but it’s incredible useful. I can’t wait to get it back.
If you’re desperate to use it, like I was with a recent freelance project, you can use 2.79. There’s absolutely nothing wrong with using an old version of Blender.
