As we haven't got an obvious 3 I'd be asking Denly to do it as a stop gap or trying Balance again, then Root can move to 4. After that we've got lots of options of Pope, Stokes, Bairstow, Butler etc. Not sure we've got that many openers to ask to bat 3!
I'd probably lean towards Ballance myself, at least we know he has the capacity to score big runs if he can get in. Beyond that it would just be choosing who to throw under the bus! Think a big problem in this series has been our celebrated lower-middle order has been rubbish! Apart from Stokes, noone else has played a really significant innings. Can't see how we can keep Buttler and Bairstow in the same side, opposite problems in that Buttler is performing ok and improving but has struggled to play the big innings (not entirely his fault tbf), whereas Bairstow at least has proved he can get the tons but is going backwards faster by the series. Got to find space for Pope somewhere imo, it's been a long time since England had someone in the number 6 'promising apprentice' type spot (Bell?). Sort the top 3 out, hopefully get the best from Root at 4, get Pope in then the rest of the order gets easier, it's just about choosing a keeper.
More on the topic of this match, it's depressing how predictable it's getting by this point! England struggle to an average score, openers go early, Labuschange and Smith bat comfortably, Archer gets overbowled and Woakes hardly bowls.