Most of the things you say about brothers and sisters are true, unfortunatelly... many do things not for Jehovah, but because it's a way of becoming "somebody" in other people's eyes.
But I don't see this change as a potential "marking" of people who don't want to pioneer. I think it's a good thing if this becomes permanent, and there is more than one reason for it: first, people who always wanted to do more but don't find time for 50 hours, can now pioneer - because the truth is, if you don't make a comittment about how much time to spend preaching, you are more inclined to stay in front of tv or computer than go preaching, but if you know you have to fulfill your promise you organise your time so that you can do this.
Second , those pioneers who now think they are "somebody", an incredible special and spiritual person, will probably fell more normal, if they see that 50% or 30% of the congregation is like them.
Third, those who pioneer will have more time to studdy, and in case they do this for the wrong motives or in case they think highly of themselves, by studying more, they can get the right motivation and the right view of themselves.
I know theese are good case scenarios and that it can also turn into the situation you described... in this case, If I would not want to pioneer and if they would ask me why I don't pioneer, I'd complain to everyone how bussy I am and that my work barely lets me any free time, etc.... They'll understand and even feel sympathy for you and blame this system of things and satan for the fact that you can't find time to pioneer even if you want this very much..... so don't worry about this being a marking thing... it won't happen, not on a long run. Even if this arrangement would be permanent, in the first month there will be a lot of witnesses who will be pioneers, and in time there will be less and less, even with 30 hours. At least, that is what I think. But we'll see...