Is it time for some sort of alternate degree to a PhD beyond a Master's? Showing, essentially, "this person can learn, implement, validate, and analyze the state of the art in this field"?

Thats what we call a Staff level engineer. Proven ability to learn, implement and validate is basically the "it factor" businesses are looking for.

If you are thinking about this from an academic angle then sure its sounds weird to say "Two Staff jobs in a row from the University of LinkedIn" as a degree. But I submit this as basically the certificate you desire.

That sounds precisely like the function of a Ph.D. to me.