Some narrations mention that the one that fasts Ramadan, his previous and future sins are forgiven!
Is this referring to all future sins and does this include major sins?
It refers to the minor sins of the past year. Major sins require tawbah and according to some, Hajj mabrur.
As for the part which says future sins forgiven or the next year, this has been weakened by some scholars and they say any time a Hadith says sins forgiven for this year and the next, the part which says next is weak as how can a person’s sins for thr next year be forgiven in advance?
Some argue this was just for the Prophet (saw) and they also argue that the narrations in Bukhari and Muslim, which mention past sins forgiven, rarely if ever mention future sins being forgiven.
Allah knows best.