Hi N.,
It depends on your parenting style. This was not a battle I fought, except that at a certain age there became 'rules' for when my daughter could have her paci - so, for sleep or whatever, but not just stuck in her mouth walking around. I think we did that a bit before 2 - when you can start to have actual conversations with them. Also, just don't let them talk with it in their mouth, have them remove it when you guys are 'talking' so he learns that is the correct behavior.
I would say that if you "need" him to give up something that he needs for comfort then you should help him replace that item so that he can still learn the practice of self-soothing. It's the same process, but you've just swapped out the paci for the teddy bear or the truck, which you might consider as more socially acceptable.
My daughter gave hers up on her own around 2 1/2, I think. I did say that there weren't anymore at the store, so once those were gone they were gone and she better keep track of it if she really wanted it. I also did a lot with teaching her to self-soothe in a variety of ways (coaching her to take deep breaths, thinking of her favorite calming activity, sleeping with a teddy bear, using a doll to pat her back so my daughter was the soother to "help" the doll or the animal calm down etc etc) so the paci wasn't her ONLY source of comfort.
As far as the flight - if they are on a sippy cup fill it with water and have them drink slowly a couple times during takeoff and landing (or get one of those cups with the straws, if they can do that). Swallowing will have the same effect as the sucking for the ears.
Have fun on your trip!