If they are going to do Heir Of The Empire, or a riff of it, as part of this “climactic story event” I really hope they don’t bring back Luke, Leia and Han for it. Be it through Deepfakes, CGI, a mixture of both, or a recasting.
I would imagine that this will be a weird conglomeration of legends and canon material with the original characters being sidelined to focus more on the Filoni & Favreau characters. I think at most they will make cameo appearances, but it will likely be through deepfake and/or de-aging. Once Ahsoka is out we’ll be in much better place to speculate whether or not this will actually be an Heir to the Empire adaptation - but I definitely hope it will be to some degree.