Full article is over at NPR (link), but here's the gist of it:
Faced with difficulties in applying fundamental theories to the observed Universe, some researchers called for a change in how theoretical physics is done. They began to argue – explicitly – that if a theory is sufficiently elegant and explanatory, it need not be tested experimentally.To which I can only reply: You get back in there and come up with some concrete, falsifiable predictions that can be measured in this universe as we currently understand it. Otherwise, it's not physics, it's not even a theory. At best... interesting preliminary calculations. Concentrate on connecting this body of work back to something observable. Or keep plowing ahead, hoping that someday something observable will be show up. (There is a certain heroic, possibly tragic aspect to this approach, so long as the quest for a concrete prediction is not forgotten.) Or, shelve it next to other promising lines of research that didn't pan out. It wouldn't be the first time that good scientists have had to do this. But put aside this "we don't have to make observations" nonsense.
For a longer, more nuanced discussion, here is the original article in Nature.