The campaign is finished, and it did wrap up quite nicely even though I wasn’t able to post updates. I got very busy with work, so I delegated the GM responsibility to one of the players (who is also an experienced DM). He did an excellent job, and it reached the planned ending at 30th level. The rest of the game went something like this:
1. The PC’s successfully convinced enough factions within the Imperium that defeating the illithids was feasible. A great civil war divided the Imperium. Great battles were fought, and devastation wracked both sides.
2. Behind the front lines, the all-wizard PC group opposed the mindflayers of Penumbra in desperate “Science War” (think WWII, with German and American scientists racing against each other to complete the Manhattan project first).
3. Illithid scientists neared completion of their project “Ascension,” in which their race would transcend to its next nightmarish stage of its evolution. The ascended illithids would have no need for other races, and the ascension process would eradicate all life in the multiverse. [The process involved the entire multiverse and the undead “zerg” race (the xtltlxl), but the details are unimportant].
4. The all-wizard PC group divided a last ditch strategy to hijack various elements of the illithid’s ascension project and “reverse the polarity.” This would eliminate the mindflayer race instead of ascending it. Unfortunately, the plan required a direct assault on Penumbra itself.
5. The final battle was against a circle of Elder Brains and their minions, and the PCs were victorious. Both the PCs and the mindflayer race were eliminated from the multiverse’s timeline entirely and history was rewritten. The rest of the world appeared as though the mindflayers had never arrived from the future 13,000 years ago, unaware of the nightmarish existence it had been spared.