Wanna know what my preference would be, CBS permitting?
A trip into the Nexus?
When the calendar rolls over to 2410 officially, we're due for it to return.
Maybe it could be setup so that once it comes back through, the Hobus Supernova will have adjusted its path so it gets stuck in a one year repeating cycle and we could have, in the future, the Picard Christmas zone and Kirk's ranch open up as Nexus zones from around November 1st through January 2nd or so every year, with reward events tied to them.
I can't imagine that being ready THIS year but that's whatI'd like to see longterm: Holiday Nexus event. And it's a longshot but I'd love it if Guinan's echo was the host of the event. So you know every holiday season that Guinan will send you on a bunch of Nexus holiday adventures.
As an alternative to that, it would be awesome to have a Holiday on the Edge of Forever mission where we go back to Edith Keeler's mission to clean-up any damage and take care of the homeless people displaced by the head of the mission being killed with Salvation Army Santa disguises (to avoid contaminating the timeline). Maybe to tie it all in a little better, we get sent by Gary Seven's agency (which is faction neutral) and are investigating someone who doesn't belong in that era. That would take maybe half a dozen new costumes and a bunch of new building assets though.
Heck... What if we were investigating a bunch of Romulan temporal saboteurs? So you've got a bunch of pointy eared people in a secret workshop that gets conflated with elves.