How long do you think Naruto can keep up Kurama's cloak on everybody? 15 minutes if they aren't getting damaged? I don't think it takes to long.
Now the problem with Kurama's cloak is that we see Naruto owning on the power scale. It started when he decided to assist every battlefield in roughly the same time. Also one Naruto on the battlefield could change the tide of the battle.
In the following chapters we are going to see Naruto YET again exhaust himself and then what. Sage mode? Probably but it's more likely he will collapse like he did in volume 66.
Everyone forgot Shikamaru's words from 1 or 2 chapters away that if they wait for an opening they could do just as much damage as the others ( Madara, Obito, Juubito, Naruto, Hashirama)