I don't see him (Shumpert) hitting 4 threes in another game this series regardless of who covers him, but it's not as important once JR gets back.
And Pau is going to be a problem all series. Mozgov can't get out on him, so it has to be Tristan, and while Thompson is very valuable for his offensive rebounding and the fact that he can switch onto guards and hold his own, he tends to be out of position and he's not exactly the best one on one defender. Pau can still score on him effectively, not sure the Cavs have an answer for him.