In the future you should just not give a set date for release, and simply release it when the update's ready. Or maybe say, within the next few months or something like that.
Set dates are good, since that gives a dev a goal and keeps them on track, keeps them focused.
Besides, months and months between updates is FAR too long, unless each update doubles the content. (If FL took THAT long, Project Quimbly will beat him to the punch and make his game irrelevant, anyway.)
Disregarding the competition, without deadlines, you get those devs that make 10k a month on their Patreons and update the game maybe once every six months, and half the time they're talking about going to conventions or buying a house instead of talking about their games.
Still, FL is two months late now and only posted that credits post which didn't really give us much info. I wouldn't mind as much about the delay if it wasn't for how quiet things are.
I'm not too worried about this game becoming 'irrelevant'.
No offense to Team Quimbly, who are clearly trying their little hearts out, but based on the current state of that game, plus the lack of meaningful content updates since it was first uploaded, It'll be quite a while before it reaches, let alone surpasses A.B.L. in quality.