Without fail, every time I'm on a plane I witness a flight attendant shoving someone's over-sized carry-on into the overhead compartment. Checked luggage charges are pretty much unavoidable (unless you fly Southwest), and passengers are trying to skip the extra fee by jamming as much stuff as possible into the biggest carry-on bags. I appreciate the fact that people are trying to save the cash, but I'll admit, the practice does get under my skin when it starts eating up everyone's loading and unloading time.
Passengers aren't going to stop bringing luggage and there's not much left for airlines to place additional fees, so there's speculation that carry-on bags will be the next target. Some passengers might welcome the charge which could create a smoother experience overall, while others would undoubtedly take offense to this type of fee.