From the various reports and tweets I've seen lately, it sounds as if all of these rumored series are being considered, but that nothing is even remotely concrete yet. In other words, I'm sure a good chunk of these series are in some form of development, but it will all come to down to actor availability, budget, etc.
For the record, these are the SW series currently being rumored that I'd actually put stock in...
- A Lando Series (pre or post Solo)
- A Lando + Han Series (post Solo)
- A Qi'Ra Series (pre or post Solo)
- An Obi-Wan Series (post Revenge of the Sith, pre A New Hope)
- A Leia Series (pre A New Hope, as a young teenager)
- A Finn + Poe Series (pre or post Episode IX)
... while these are being rumored as well, but seem a little iffy...
- A Captain Phasma Series (pre The Force Awakens)
- A Knights of Ren Series (pre Episode IX)
- A Rose Tico Series (yeah, I know, spare me the outrage - pre or post Episode IX)
- A Sith Lord Darth Bane Series (this is one that tipped this batch into the "iffy" category)
... in addition, of course, to the two confirmed series...
- 2019 - The Madalorian (post Return of the Jedi)
- 2020 - A Cassian Andor Series (pre Rogue One)
... and again, for the most part, these likely aren't being developed as multi-season series, but rather each would essentially be an eight-episode (or so) limited series/"movie," though I'm sure lengths and potential season orders will vary.