Nah. Entire games can be built around the holidays. One of the James Bond games has you "saving new years" And plenty of games have Halloween or Christmas DLCs that essentially add things in like "winter" golf courses, or halloween horror content... etc. etc. They're enjoyed all year around.
For something like this, even if the "deadline" has been missed. For a lot of us, we can easily be transported "back to halloween" just by seeing the update and content you have at the time. So long as you can maintain your vision for BFS9 - Halloween Edition, so can we! As long as you're feeling the pumpkins. Or the Christmas sleigh bells. And can convey that on screen, you don't have to worry about deadlines. And designing seasonal content can be a really good way to maintain working on the title. It gives you framework to work off of without having to like... design content (say a sequel) from the ground up. And lastly, if it's a really good taste of the holidays? Then people will not only enjoy it when it comes out. They're replay it next Halloween and Christmas too! (I still like going back to Castlevania Lament of Innocence and Curse of Darkness just because they have unlockable halloween characters/costumes/abilities. That's how I ring in Halloween!)