NASL effectively folded the beginning of 2018 season when USSF did not sanction them for competition. USL was 3rd division in 2016, went up to 2nd division in 2017, as was NASL. USL continued as 2nd division for 2018 (with 33 teams in 2 conferences) while NASL lost several teams (down to effectively 3 teams with Puerto Rico's status still up in the air) and spent the last several months in and out of court with USSF.
USL created a 3rd division and has rebranded 2nd division, 3rd division, and PDL into a unified structure: USL Championship, USL League One, USL League Two.
Also standing up with a fall/spring season is NISA, National Independent Soccer Associate as 3rd division (if they get USSF sanction), currently with 3 or 4 teams officially announced? Not sure because their communication is pretty terrible.
NPSL Pro is supposedly happening with some of the NASL legacy teams, but still unknown.