Does anyone have a list of mods confirmed that we will never see for SE?

I'm not really aware of any. The word "never" is pretty strong. The only mods "confirmed" to "never" make it to SSE would be those mods whose author has confirmed they won't allow their mod to be ported to SSE. That would constitute confirmation that the mod would never make it to SSE, but even then, people sometimes change their minds.

And even then one could still do it for one's self, so long as you don't release it to the public, it isn't like the mod authors could stop you.