There are already 8-man duty support versions of The Mothercrystal, Worqor Lar Dor, and Everkeep, so Im confident they can redo the old 8-man MSQ trials of the past regardless of whether they are a final fight or not. As others have mentioned, it is likely gonna take some time though. I just figured they would prioritize those over optional dungeons such as Halatali...
Even if they choose to keep final fights out of the equation, there are many trials that would still benefit from Duty Support to ease the burden of progressing the MSQ.
Leviathan, Moggle Mog, Ramuh, Ravana, Bismark, Susano, Lakshmi, Tsukuyomi, Titania, Innocence... to name a few.
Anything that eases the bottlenecks to MSQ progression would be a boon.