I really don't see these guys being internet evangelists with checks rolling in. To get members' money, they have to meet. I can see congregations becoming smaller due to attrition and people being told to go further to a hall and others being sold. I can see them abandoning Kingdom Halls sometime after that and trying to have regular/semi-regular meetings at assembly halls, sort of the mega-church atmosphere. But that's pretty far down the road, and they would really have to get money from those attending if they only come every once-in-a-while.
Otherwise, they will pass on all the cost of printing to the locals eventually. They will not have to print as they can just carry a "device" with all they need on it.
I see them selling their glorious new headquarters, but not for decades. I see them fading away, I also see it taking 80 years or so, but lawsuits and damaging news about pedophiles and cover ups can speed it up.