I am sure many people will dislike the idea, others will say it is simply not d&d. I am not even sure if I like the idea, but as you know there are no bad ideas when brainstorming
What about bringing a adventure pack with visitors from outer space i.e. aliens? Imagine:
guild ships on their usual track recognize unidentified flying objects. wildlife animals go crazy. some quests (some fights, some puzzles), final part destroying mothership (as usual, maybe option to make peace with them). Bringing some extraeberronial artifacts (gear, weapons, nothing overpowered, just nice visuals like repeating blaster/laser crossbows, or some niche CC weapons, like blaster guns with 3 charges/rest of a targetable otto's disco ball). everything is possible.
maybe too daring idea. or time to play XCOM again. 8)