Right I've been rewatching and reading online and thinking about it and here's my theories:
Vader/anakin will return. Jinn was able to communicate after his death; yoda and obiwan knew about his studies and the immortality and at the end when vader is dead you see the two of them and anakin. Anakin was by far the most powerful user of the force; I reckon Luke's been at the original Jedi temple studying the ancient ways. Rey has got to be his daughter; together they will bring back granddaddy anakin and he will stop kylo ren either by redeeming or destroying him.
But will it be vader or anakin who returns???
(I reckon anakin, he was the chosen one and I reckon he can still fulfil his destiny)
Anyone agree/any other theories?