Advertise the website and donate. That's all they need to know.
And provide free labor for real estate development.
The preaching work is a relic of when it was actually profitable. Tax law changes screwed them over a bit on that, and I think the JW culture is shifting to the point where most going d2d don't remember the days of asking for money so they're uncomfortable asking for donations. The magazines are so cheap and flimsy and come in bountiful supply, so most probably don't even factor that in when they donate.
If this cult is still around in 20 years, I wouldn't be surprised if they phased it out altogether and replaced it with the important work of building kingdom halls. That's a big change so it'll take time so no one will notice, but they're already on their way with the website and the carts.