Nope, Xehanort is mega deadity-dead.
His heart and body were consumed by the darkness. I don't think they'll revive him because his heart and body merged again in the darkness.
That would make him unkillable.
Kimi wa ne tashika ni ano toki watashi no soba ni ita
Itsudatte itsudatte itsudatte
Sugu yoko de waratteita
Nakushitemo torimodosu kimi wo
I will never leave you