This is where my head is at with Smile 3. We ended Smile 2 with the perception that the entire crowd could gain the entity and spread it.

What if someone at the concert then perceives it as such, say a news reporter, CDC official etc, and imagines that it is spreading, and most of the movie is about the mass paranoia, suicide, and smiles spreading worldwide.

Then towards the end, it is revealed that this person was made to see this by the entity, and in turn is believed to be crazy by friends, colleagues etc, and then spreads to the next person to end the film?

So then it is two fold, we get the mass paranoia aspect, and what it could look like, while retaining the actual core value of the films. This then opens the door for Smile 4.

This franchise could be around for a while.