Ephesians 4:11 makes for a strong case that not every member of the congregation should have to go door-to-door.
"So Christ himself gave the apostles, the prophets, the evangelists, the pastors and teachers,.."
This shows that different members of the first century congregations served different ministerial functions. So why don't the JW's say that field service is no longer compulsory for all congregation members, only for those who feel a calling for it per Eph 4:11....
The Mormons sort of do this with their young men and women 'elders' doing 2 years voluntary, genuinely full-time service (these Mormons boys put in some BIG hours 6 days a week and have their meals provided for them, etc!), riding around on their bicycles in the local communities. After their two year stint they have served their time, they go home, and then just go to University, get jobs, etc, ie, just go and live normal Mormons lives.
JW's could come up with their own version of this. For example, why don't they just leave the door to door work to the 'pioneers' only and arrange for the congregation to support the pioneers practically through providing lunches, dinners, accommodation etc, just like the Mormons do?