I have no issue with a big gap between Solo and IX. I am not certain that the current relentless release schedule is necessarily a good think for the long term health of the brand. Star Wars should never become humdrum. I feel we risk over exposure at the moment, and as someone who likes collectibles, it seems like licensees never have time to cover each film adequately before they're off and running towards the next.
As far as that big window between movies goes, I think we should expect a new animated tv show to debut at some point between the Solo flick and IX, so this is probably good news for that show. It has seemed to me like the tv series have tended to be lost or ignored with marketing licensing focus being on the feature films.
To Archon's point, I have been expecting them to announce Solo being pushed to December ever since Lord and Miller left. It is surprising to me that they haven't done that. It would make even more sense now.
As to JJ being back, while his movies have great energy and charisma, he wouldn't be my first choice. TFA was fun, but thin and entirely too derivative to be completely satisfying for me. JJ is good at setting up intrigue, but he is way more interested in questions than answers. It is clear that TFA's mysteries were thrown in without any thought towards their eventual resolution. In fact, I can't remember the last time I ever felt satisfied with the way one of his projects concluded, so I have some concerns about this choice of having him write it even more than direct it. Meaningful pay off just doesn't seem to be his thing.