This is the connection between baggage checking and carry on bags.

Since September, I have checked the bag I would have carried on in the past. I usually board with a with a book and a few other items. If I was traveling with it, perhaps a laptop too. Previous to that I have carried on a regulation carry on with a couple of days worth of traveling in it, not wanting to check a bag if I could help it. It's been easier to check the bag, because there were things in it that were allowed before September that were no longer allowed (razors etc).

Now that the delay might be at the screening of the checked baggage, instead of checking a bag next trip, I am now more inclined to check the absolute minimum of stuff I can, which would be the things security if frowning upon now. I will carry on the rest, because x-raying a carry on is faster then hand searching each and every item in it.

For me, that is how the new rules will increase carry ons. I wouldn't have had one before Friday, after Friday I will.

Everybody who doesn't see the connection appears to be assuming that each person on the plane is already traveling with a full sized carry on, which isn't the case at all. I think that many of the people who were not will be after Friday though.