The details of the 35th Anniversary Edition has been known for a while: https://www.motor1.com/news/352286/chrysler-dodge-minivans-anniversary-pricing/I guess the 35th Anniversary package is the 'big' news for 2020. Hopefully, there will be some better news for mid-year introduction.
It will be nice to get power folding mirrors and memory seats on other models, though.
I thought it would be available as a mid year 2019 option, it didn't happen. It is highly likely that the pictures in the link show the 2020 model. Which means no visible changes besides the 35th Anniversary bling. 2020 can still bring not so apparent upgrades, for example HIDs on the Hybrid, however it won't be a mid cycle refresh or radically new entertainment system.
The active safety features may come to the lower trims, but niceties like the power folding mirrors or memory seats are never going to migrate downmarket- this how FCA spreads butter on their bread.