Some people are getting really excited about this, but I will be more realistic in this.
At first good news. Being able to rejoin with not penalty if my kid drops over my internet cable is great. Kudos for that !
But now comes the bad news. TC and GoW franchise will most likely (you know, never say never :) ) not be able to implement really punishing quitting penalties which are available in some heavily played franchises. For example I can speak for Counter Strike (back in the day. Not sure about its status now), others are mentioning League of Legends, Rocket League etc which I cant confirm as I never played those. ... Guys, you have to keep in mind one major thing. Those games have much higher player base than GoW. If they will block thousands or even tens of thousands of people because they are leavers, you will still have a lots of players of your skill which you can be matched against. ... If you will do that in GoW, you will be playing either alone or the matchmaking will be so broken, that the game will be totally un-enjoyable for you.
So overall yes, there will be quitting penalties, but TC can implement only something very decent, because they cannot divide already small community.
I have a great example in another game I play a lot. Real time strategy Company of Heroes 2 on PC. Great game, small player base. Usually like 5 - 7 thousands of people are playing when I am searching for a match with friends... People are calling for quitters penalty in team games for nearly 4 years. But still nothing implemented. Why ? Because even now it takes several minutes to find you a team match and even than you are sometimes placed against players from top10 world rank. ... Imagine if quitting penalties were implemented. You will be waiting longer and be placed against much more (or less) skilled opponents.
But what Company of Heroes 2 implemented and I can see something like that in Gears of War is that they replaced the quitters with AI. The only problem is that they still didn't figure out the level of AI so it will be an adequate opponent.
I don't want this threat to be throwing dirt at TC, community, GoW franchise or whatever. I just want to calm down some maybe overly optimistic players who thinks, that quitting in GoW will magically disappear within TU3 and TU4.