If there is revenue to be realized in checked bags I don't think the airlines are going to allow much "abuse" in the carry-on rules anymore.
I can hardly wait to see the abuse of the overhead bins that will begin soon
There was a time when they allowed massive carry-on abuse because it lowered their cost of handling checked bags, but now that the checked bags are revenue producers you can pretty much bet carry-on regs will get more attention and tighter control.
To be honest, compared to what I paid domestically 20 or 25 years ago, airline seats today are really inexpensive. Myself, I don't have to much issue with the baggage charges. It's either pay more or have fewer airlines, flights and options. That's tightening up already.
In my view flying across the country for a few hundred buck, or now for a few hundred bucks and a couple baggage charges is a steal. And if I have an emergency or don't book early enough to get decent prices...well that's just the the way the ball bounces