I was checking the Tauck website today for the new Seine holiday cruise and whether the 2026 dates were available yet. In the process I discovered they are having 2 new ships built for the Seine and the Rhone for 2026. The data on the website is a bit garbled but it looks like both will only have 5 cabin categories - mostly 300 sqft suites on the Diamond deck plus a couple of 225 sqfts, all 225 sqft cabins on the Ruby deck and mostly 150 sqft cabins on the Emerald.
As I said, the info on the website is a bit confused so I sense the final design hasn't been locked down yet. Interesting that they look to be getting rid of the triangular cabins at the front of each deck. It kind of feels like the way they went with the Douro's Andorinha's cabins. As a bit of a nerd wrt river cruises, I'm looking forward to seeing how these ships are going to be designed.