This summer i’am planning to cycle from Dali tot Shangri-La and back. Someone who cycled this route last year wrote that they were building a new guesthouse between Sangri-la and Baishuitai. Is that thru? Is it open yet? Anyone?

If you're in reasonable shape and altitude adjusted, it's possible to ride that section all the way in a day.

Indeed you have to be altitude adjusted and very fit. It is only a hundred kilometres but 6200 meters up with a highest altitude of 3740 metres.
No idea about any accomodation after Baishuitai but some years ago that I did that stretch (however plenty in Haba and Baishuitai).

'...6200 meters up with a highest altitude of 3740 metres." - ???

The road goes up and down. Total climb 6200 metres total down some 5000.