Obito is only worthy opponent for Madara. Of course Obito has no hope in landing any lethal damage to Madara, not even mentioning killing or destroying him.
Obito's main role should be focused on stalling Madara and leading to revive main heroes who revived with asspull power up given by Kishi will let them win against Madara. They may use help of everyone or no, but still Madara is main heroes problem.
This is only for Obito to get his redeeming by stalling Madara giving hope to alliance or even injuring him a bit then reviving true hope for the world Naruto Uzumaki himself.
Besides Hagoromo Ootsutsuki solos
EDIT: I would love Madara to regain his Rinnegan from Obito then double Rinnegan Madara vs double MS Obito(after lending his original's eye from Kakashi). It would be one hell of battle.