Even though I like clojure and think it's cool, I don't think VimL needs another layer that slows it down. I'm putting my money on the VimL to Lua translator that's currently being worked on by ZyX-l (https://github.com/ZyX-I/neovim/tree/luaviml) for neovim. With that, we can run VimL as Lua code in LuaJIT, which will transform VimL from one of the slowest scripting languages to among the fastest.
Note that I said among the fastest, because VimL uses native integers which Lua doesn't have. LuaJIT does have them but their conversion rules are different so there has to be some shim code (https://github.com/neovim/neovim/issues/392). There's also many other VimL -> Lua incompatibilities that will incur some slowdown but it should be wicked fast still.
Of course, I expect that many people will start writing native lua plugins after a while, it is a far more pleasant language, after all.
Note that I said among the fastest, because VimL uses native integers which Lua doesn't have. LuaJIT does have them but their conversion rules are different so there has to be some shim code (https://github.com/neovim/neovim/issues/392). There's also many other VimL -> Lua incompatibilities that will incur some slowdown but it should be wicked fast still.
Of course, I expect that many people will start writing native lua plugins after a while, it is a far more pleasant language, after all.