It will likely depend on how full the plane is. I flew Delta from Lansing, through Detroit, and on to Orlando in April and the plane was jam packed. They pulled a bunch of us with carry-ons of the legal size and had us check the bags at the gate. (Everyone in Zone 3 or something like that.) They were not, however, "gate checked" as usually understood. We had to go to baggage claim to pick up our carry on bags. I was not happy.
When we flew the same route last month, it was still a crowded flight, but there was more room and they didn't select a loser group have to check their carry-ons.