EHGNA is dead and gone into bankruptcy. The Hymer and Carado brand names are now owned by the Thor Company. And they are orphans.
Roadtrek is now Roadtrek, Inc and is owned by the French company, Rapido. (they have a number of products in Europe, including the Westfalia) They have a new website up and running and seemingly pretty updated. They will be selling the Zion, Zion SRT, and RT's old Sprinter line for the next year or two. They hope to have the rigs at dealers next year.
Roadtrek rarely, if ever, did upgrades on their older units. And I doubt that Rapido plans any such projects. The rigs currently on lots do not have a warranty from them... as I understand it. It is rather a case of having to provide your vin to check with their warranty department which is now up and running. If you start dealing on a unit, call the factory and ask. You will, of course, still have the Promaster and appliance warranties.
2019 Roadtrek Simplicity SRT (almost a Zion)
2015 Roadtrek 170
2011 LTV Libero
2004 GWV Classic Supreme