I think Ford will be producing 350/450 Cutaways & Chassis Cabs past their original discontinue date of 2019. They currently supply the RV industry with over 20,000 cutaways a year. However the current upgrades on the Transit (including GVWR) are a sign of change in the near future.
A Mom, a Hiker and a Deliveryman Walk into a Showroom; Each Drives out in a... (https://media.ford.com/content/fordmedia/fna/us/en/news/2019/03/05/2020-ford-transit.html?fbclid=IwAR2X1wW-e4C5AypLACqQN4JI18Wq4a7LP4HkZyDLfdUv3LYXBTtV6AAZZTs)
For those like the spec sheet
2019 Ford® Transit Cargo Van | Model Highlights | Ford.com (https://www.ford.com/commercial-trucks/transit-cargo-van/models/transit-van/)