We know that tadpole you get is not the usual tadpole. It was made up to accomodate needs of the game. I will wager that we won't be able to remove it that easily, out initial attempts will fail, because it is a different kind of tadpole and it will remain through the enitre or most adventure.
It's been said that giving into tadpole give power but corrupts - as well as taking or rejecing this power will be one of main throughlines in BG3. I don't think it is a big jump to claim that tadpole and embracing or rejecting Illithid is BG3's version of Bhaal heritage. I also think it can be very much like source in D:OS2 - something that ties companions and coop players together and includes them in narrative, over-riding any personal needs or motivations an origin or custom character might have.
There are too many things tied to the tadpole (explanation for your superhuman abilities, connection to companions, ability to read each other mind and share experiences) to just remove it in first act. Collar in D:OS2 supressed abilities acting as a tutorial gate in some way. Tadpole is the source - it is through it that gameplay system are being implimented/explained.
Maybe we learn it’s not actually killing us or just killing us very slowly? Or maybe we’ll be able to remove or neutralize it while the effects it had on us remain?
I agree that powers/corruption will likely stick with us throughout the game, but I expect the idea of a ticking clock will be resolved by end of act 1 (if there is such a thing).
While I like having a sense of purpose (or one of several purposes) to drive the story, too much urgency and impending doom can make it hard to justify wasting time exploring and dicking around in the game world for your character. You always feel you should just get on with dealing with your problem.
Also I’m not sure that the thing you discover in the opening cutscene should be your main motivation throughout the whole game. I’d prefer some unexpected turns in the story. Continually trying and failing to remove the tadpole doesn’t sound all that appealing.
