Well done @UncleDave . And an excellent post.The way we did it was less "cutting them off" than "weaning them off" living at home. We implemented the tiniest bit of tough love and ratcheted it up slowly.
Kids could live at home during school.
After schooling As long as they were working and saving for a place and following mom's rules it was all good.
Not working, or looking for work, hanging out all day playing games while enjoying the amenities and services only lasts a matter of about week before ever more restrictive measures got implemented and they didnt have to go far before they got the picture.
By restrictive measure I mean - killing power to their room during working hours and blocking internet access for all but a few hours a day, enough to get resumes out but not enough to play games.
Cant find a job? No problem I'll find one.
Son #1 went to work feeding the homeless at a soup kitchen (for zero pay)
Son # 2 went to work for the local shelter helping with the animals walking feeding and cleaning pens (for zero pay)
You either contribute to the house or society - lo and behold they found paying jobs right away.
With the jobs came rent, and groceries, and a workable share of all the bills and them doing the shopping in rotation.
Mom and I still laugh about their first trip where they really had to shell out some bread - " I cant believe how expensive laundry soap is"
Our boys were really good kids, and there was no "law" that ever needing laying down or awful behavior like so may endure - we just weren't going to let them be lazy young men.
Both boys are pulling sold 6 figures, one I was able to open a door to the TV industry for, and he's an engineer for NBC set for life.
The other boy a a successful software developer just moved into his own townhome.
We tracked all the money they paid in and gave it all back to them when they bought their first places.
You outline a plan that many people could follow. Tough but fair.