I dont see Metroid Prime ever returning. This whole thing was a decade long costly nightmare for Nintendo that now may not even meet the very mild sales standards of the other Prime sequels. I think Nintendo abandons 3D Metroid for awhile to focus exclusively on the 2D franchise, and then maybe they will eventually return to a new take on 3D Metroid. Would he cool to see it developed in house after so long.

The Switch 2 version still hasn't reached a million so considering that version makes up the clear majority of sales it could very well still be below 1.5m currently. At this point I doubt it'll ever reach 2m so it is doing worse than I expected. The not ideal critical response and word of mouth really did hurt it seems.

Last weekend I was at my local retailer. I know this is anecdotally but shelves where full of Prime4 and discounted heavily.

Switch2 Prime4 which launched at EUR79 physical here and now are EUR49.
Shipped to retailer is a sale for Nintendo, but if there is slow sell-through, we don't see retailers re-order the game and have Nintendo do another print run.

Yes it is. Nearly 175 million consoles total and Metroid Prime 4 can’t reach 2 million sales.

From a front heavy franchise at that.