Nintendo is definitely doing a good job pushing it in the usual spots. More than what we can say about Samus Returns. They definitely want this to be a better performing game for the year.
Knowing that, previous brand releases tell me it won't connect with the general masses, so we should not expect a Animal Crossing type situation. I do expect it to get some decent results, but nothing massive. The Japanese hype is not significant enough to make a big splash there, so we're left with the West to bring it home.
This is the first 2.5D Metroid on console, so we're in uncharted territory. What we do have charted is Metroid on console, but the only "recent release" comparison besides Prime would be Other M. Other M collapsed within itself at launch, so that would be a bad consideration. The other charted territory is 2D Metroid. Outside of the older titles which never passed 3M, the newer 2D games never really reached that level of height and stayed on handheld platforms.
So I think this will comfortably outsell Samus Returns (it only did half a million? and I'm actually sad for Fed Force).
Crossing 2M could happen, but 3M might be where it gets shaky.
I want it to go higher - Switch hype and all - but I think if you look at other Nintendo IP in that zone of fanbase, it has a bit of a ceiling. I chose 2-3M, but I think the ceiling is 4M. Will gladly eat Chozo.