What if meetings were like fast chess, where each player has a strict limit on total time? When you talk you start your chess clock. If you go over your budget you must be silent for the rest of the meeting.
You could also apply this to days as whole. You get 2.5 hours for all meetings together, and when the limit is reached you must say no.
How about rewarding attendees who wind up with a time surplus at the end of a sprint / week / month.
What about side-dealing, where Alice cedes the balance of her remaining time to Bob (or to the floor for first-come-first-serve consumption)?
I envision employees with a side business selling their excess time to overtalkers.