Use again Nseries brand on high end Nokia smartphones.
Nokia 8 -> Nokia N8 (2018)
Nokia 10 -> Nokia N10
I would love to see a true return of the N-series. Top imaging and top audio are two things that I really value in a smartphone.
Lots of people already refer to the new phones as N6, N8, etc. and I believe that the general focus of the HMD Android phones is similar to the focus of the old N-series, but not quite at the pinnacle of imaging and audio.
In the 2000s Nokia had so many different models it needed to use the N, E, T, X etc series to help differentiate them. HMD only has ~10 phone models, so no need to add another letter to differentiate.
I hope we'll see a new N-series in the future :)