I read that rumor several days ago and brushed it aside (though the possibility amused me). Since then, Google on my phone has been inundating me with more (at least half a dozen) other articles about it. I haven't read them to see if they all have the same source, but the rumor is definitely one of the hottest topics right now.
They're likely not going to retcon the sequel trilogy until they have a good reason to do so... i.e. a movie or series that they want to make that they couldn't, otherwise. For example, say that Favreau wants to make a series similar to The Mandalorian, but about Luke coming out of retirement to mentor a young Jedi and go on adventures with. I could see something like that because fans love Mark Hamill and he loves the character and the franchise so much that he'd surely return (despite saying that he's done playing Luke, which I think was more a reaction to being killed off and not wanting to play a Force ghost of Luke any more). Obviously, for something like that, TLJ and TRoS would need to be retconned. Unless something such as that comes along that absolutely requires a retcon, however, they'll most likely try to work around the sequel trilogy as much as possible.
