While there have been several current-gen games brought from PS4/Xbone to Switch so far, perhaps most notably Doom 2016 and Wolfenstein II, I think it's fair to say there haven't yet been any quite like Hellblade, namely a high-end 30fps game with a realistic art style.
There's always the possibility it may be a poorly handled conversion along the lines of, say, WWE 2K18, but if it's manages to make the transition in a respectable state, it will redefine the parameters of what kind of games can be ported to Switch. The doors will be open to all kinds of titles that have previously been regarded as impossible.
Of course, that's not to say that third parties will suddenly throw themselves behind bringing their more demanding games to Switch.
But a lot of the conventional wisdom as to what is and isn't doable as far as porting to Switch will be turned on its head if Hellblade turns out to be good, and that's an exciting thought.