Airline baggage fees and the law of unintended consequences

This is off-topic, except for the fact that many of us fly a lot. United and American, as most have probably heard, have started charging for checked baggage. I have no particular problem with this -- the airlines are hurting, as we all know, and they have costs connected with baggage-checking, so they have sufficient justification for passing the costs along.

My only concern is whether they have thought through the consequences of incenting people to carry more luggage onto planes. Most flights I've been on recently have overstuffed luggage bins as it is, and people who try to force too-large bags into the bins are already holding up the boarding process.

My predictions: More late departures because of slower boarding, and more angry customers because of full bins.

My questions: Will they charge for gate-checked bags, and if not, will this become a way around the fee? Also, might this lead to actual enforcement of the rules on over-sized carry-ons?