Ever since he was captured, I thought and hoped that would actually be the case when he gets out. Like somehow reversing the effects and absorbing whatever Tobi had of Hashirama back into Yamato.Well i was thinking that the opposite might happen as well. Tobi/Kabuto used him to strengthen the Hashirama tree and the white zetsu... Maybe it works the other way around as well, and when he gets out of that tree he will have been strengthened by it.
Anyway i see no reason for him to loose his wood kekegenkai.