It looks like Far Cry 3: Blood Dragon - Classic Edition will see a standalone release.
A rating for Far Cry 3: Blood Dragon - Classic Edition has popped up on the ESRB's website, awarding the game a Mature rating.
Far Cry 3: Blood Dragon - Classic Edition is, of course, part of the Far Cry 6 season pass, so we've known that it's coming for a while. But Ubisoft has yet to announce whether the game will be available as a standalone purchase later on, which this ESRB listing suggests would be the case.
Far Cry 5's season pass included a copy of Far Cry 3 Classic Edition, which was later sold separately for $20, so we'll likely see the same thing happen here. It's worth noting that the Classic Edition branding indicates that this going to be a straight port of the original game, and won't offer any major new features.
Although Ubisoft has yet to confirm this, going off the Far Cry 3 example, that release was barebones, and offered minimal upgrades over the original. The framerate, for instance, was locked to 30fps as in the original, which was a particular sticking point for fans. Here's hoping Blood Dragon will offer an upgraded framerate, at least.
Far Cry 6 is out October 7 on PC, PS4, Xbox One, Xbox Series X/S, Stadia, and Luna. It's not clear when Blood Dragon will be released.