The last captain bid was full, as I would expect all future upgrade bids. With a 5 year upgrade, a lot of FO's (except those over 5 years enjoying QOL and/or too close to retirement) will jump at any chance to upgrade, regardless of base/equipment.

No one knows when the next one will come out. Rumors of hiring 300 or so more pilots are out there, I would assume upgrades will run in association to that (obviously not in such large numbers.)