E-series cutaway has been committed through at least 2019 with the vans through at least 2015.
Express Chassis can't go past a 209" wheelbase because the frame is smaller. So sticking a longer body it makes for bad weight weight balance. You can pretty much see the 30' cutoff on the Express from all the big RV makers. Plus, GM has never even hinted at a long-term forecast for the Express. THey've cancelled truck lines before with only a couple months notice.
Ducato/Pormaster is FWD. Not way would you be able to pull a 30'+ coach up any sort of a grade without madly spinning the tires.
A while back I rear one article stating Ford will stick the Transit cab on the F53 chassis for a larger cab/chassis (i.e. T550). But I haven't seen anything lately so maybe that has been put on hold. Ford is maxed on F53 production anyways because RVs made a HUGE jump in sales this year (and there is no longer Workhorse to compete with).
Transit pretty much matches the Sprinter axle and GVWR capacities, so I think you'll see see it taking some of the Sprinter market, but nothing bigger. It's main advantage will probably towing capacity (assuming they maintain the F150 ratings), and lower cost.
