"That's tremendously exciting stuff. It would surely be the greatest scientific discovery - ever. The much maligned Edward Wittens of the the world would instantly become heroes."

Nah, it isn't. One still has to prove that it is string theory and not some 4-dimensional effective field theory in the regular 4-dimensions. This is the main problem with string theory: any effects pervading from "other" dimensions can be described by a 4-dimensional effective field theory, the latter possibly less elegant than the string theory formalism. So go figure.