I think within 40 years they are gradually going to lose members due to the unfulfilled expectations.
Just my opinion, but I think the GB doesn't care about "the next generation" of JW's. These guys are all over 50 years old, so they are not really going to worry about how people will have to clean up their mess 40 or so years from now.
When you are in crisis mode, you deal with just the crisis. No long-term planning is in place. They are realizing that they cannot maintain any "growth" without reducing the requirements for being a member. Back in my mother's day, a "publisher" had to put in a minimum 10 hours a month. In my nearly 20 years active, I rarely put 10 hours in. Now, one hour is okay and some put in the 15 minutes. They have parents claiming 4 hours simply because they drag their children into the religion and there are tons of fakers on the hours.
Donations and baptisms are down- I believe the bulk of baptisms in the last 3 years came from post-1995 children of JW's- they saw the end wasn't so imminent and had kids. Those kids are now 12 to 14 and they already dipped into the younger ones for new recruits. Now, they are dipping younger and younger to get them to be "regular publishers." These ones growing up will leave and WTS needs a new doctrine to restore urgency so their parents will tell them "Just wait a few years for Armageddon."