People wanting to replace SL with one of the opensim replacement I think you have a while to wait yet.
the physics engine has a LOT to be desired at the moment. Everything is calculated as cubes, which is bad. There doesn’t seem to be a fully working economy in the options yet, the location search is at a very base level of functionality etc. It would work well if you’re into actually doing development but it’s not a functional solution for replacement yet.