Ben Solo will 100% die in this film
Leia will be killed off. So in order to 'destroy' the past and pass the torch FULLY to super-rey, Ben Solo will also be killed off.
100% extinguishing the Skywalker name from existence (all other relatives assumed perished as well).
Rise of Skywalker is the name you say?
rey can in NO WAY be a Skywalker (toxic family). She might be a nobody or it might be explained BUT she will assume the Skywalker name for the sake of destroying Luke's identity+legacy and also for disney to maintain brand effectiveness that was identified in their market research focus groups.
Thus rey becomes the 'real' Skywalker to celebrate in the franchise and all of the others can be forgotten.
(Added bonus is that they also destroy the Solo family lineage too - KK's revenge for the 'I know' line that she will no doubt remove in a special edition release sometime soon).