I think the relative failure of Solo will have a LOT more to do with what happens with Star Wars movies/tv going forward than TLJ did. TLJ still made well over a billion. It is still one of the highest-grossing films ever and it not, in any meaningful sense, a failure, even though is seems to have some vocal detractors (I’m on the fence about it, personally).
I suspect after Solo, Disney will be a bit more cautious about the ‘non-core’ star wars story movies. Which frankly I take as a blessing, I could easily see them trying to spam us with four crappy SW spin offs a year and grinding the franchise into the dirt under sheer weight of repetitive mediocrity and stretching to make films about more and more peripheral characters.
As for trailers and name announcements for ep 9 - if I had to guess, if there isn’t one in the next few weeks probably you’ll be waiting til May. It’s weird to say, but I think the MCU has such a dominant position over Star Wars in the public mind right now that the marketing people won’t want any big SW news to be overshadowed by Avengers Endgame (and possibly by Captain Marvel, if the ticket pre-sales and early reviews are any indication of how that’ll be received)