As with every fight, without plot restrictions, Obito and Madara can just launch a surprise attack and instantly win it. However, in terms of a fair, individual fight, they won't be able to take out Konoha. Sorry for all the Madara/Obito fans out there, but after 15 years Naruto and Sasuke should be above Obito and Madara. Since Sasuke is gone, Naruto potentially beats them both alone.
If Lee can open all 8 Gates, then it's rape.
If Sasuke comes too, it's just a snuff film.