It would be more accurate to say that the current scala-mode cannot be easily converted to support significant whitespace indentation. Emacs can of course support significant whitespace languages, e.g. Python and Haskell.
I have a lot of experience in this area, having written a Haskell mode from scratch. Doing the same for Scala would require such a dramatic refactor of scala-mode that it would effectively be a major rewrite. I have no reason to do that at this point in time, but it would be a lot of fun; I thoroughly enjoyed writing the Haskell mode. A requirement would be a very clear set of rules for how to insert virtual parens. Emacs also needs a forwards AND backwards lexer here, and I’m not sure if that poses any particular problems for Scala.