Re: basic explantion of all narutos chakra modes, plus how + mode will work
Far from the first thread trying to prove / predict a fusion between sage mode and beast mode, anyway, as for now it has worked pretty well with his current combination by having a SM clone, which is perfect for close combat.
It has better reflexes than BM (as Naruto said when he took out 3rd Raikage)
It doesn't take up any of Narutos chakra, since it can gather nature chakra on its own.
Blowing it up would give Naruto SM instantly in case it would be needed.
Naruto combined with ma + pa, would of course be different, since it would give him a vast amount of Jutsu, since they have a lot more jutsu under their possession, however, if Naruto alone tries to combine his BM and SM it would be pretty useless, and nowhere near as useful as his current combination. Of course you could just justify that he could still make the combo, but it wouldn't really make sense, since he still needs to stop moving etc..
I could see him combining BM with ma and pa anytime soon. It would be epic, and a lot of people miss the toads in the current battle. Also they must have some sort of importance, since the old toad predicts the savior etc., most likely some relation to the so6p, anyway, Naruto would also need some way to seal the jubi/divide it to the 7 beasts. He doesn't have this sort of jutsu, but ma and pa could have it. We already seen frogs with sealing contracts, so it's possible.