Due to Obito possessing Kamui and Madara being immortal, Kakashi is a key-player in this fight.
He is needed to defeat both Obito (countering his Kamui) and Madara (kamuing him is the only way for team 1 to win, since they have practically no sealing techniques).
If Madara and Obito realize this, Kakashi will become their main target. This is the danger.
However, as Bogard said, Kakashi can simply kamui Naruto's clone which will make Obito's Kamui 100% useless when Guy starts attacking him in 6th gate. Obito is not a problem in this fight, Madara is. He won't sit by idly when Obito is getting his ass kicked.
Guy is needed to handle Obito (force him to use intangibility so that Naruto's clone finishes him off), so that leaves Naruto, Kakashi and Bee to keep Madara occupied. Taking Obito down won't take long, so I think they can do just fine until then.
If need be, Kakashi can waste one Kamui to teleport Madara, to stop him from dealing some fatal blow. This should only be done in emergency, though, because once Madara is in Kamui dimension, he'll surely destroy Naruto's clone and then Obito will bring him back anyway.
This will be a difficult battle, no doubt. I think team 1 takes it high difficulty.
I don't see a BM clone killing obito but it might preoccupy him for a while.
When intangibility is out of the game, I'm quite positive that Obito will be overpowered by Naruto.