Board Thread:Theories and Speculation/@comment-25571342-20150809141259/@comment-4646462-20150809184304

Kurama is a chakra being, hence it's not really surprising he'd go out of tailed beast mode and change into his physical form. Besides, TBM puts out a lot of chakra; it'd be a waste to keep it activated when not in battle.

As for the ability to summon Kurama outside his body, I think that Naruto is fine as long as there is a bond between him and Kurama. If that bond is severed for whatever reason (Kurama gets sealed or something), Naruto's screwed.