Yes, George got away with recontextualizing SW with ESB's iconic twist but then as early as ROTJ the recontextualizations (sister Leia) wore out their welcome. If they want to do a twist within a self-contained story ("the Pykes were the real killers, not the Niktos!") then fine but yes no more "surprise" reveals (aka retcons) about the OT please.
Hopefully this rumored rematch between Obi-Wan and Vader will just be some sort of
vision or
test like Luke in the cave and not a real pre-ANH encounter between the two of them.