Well I'd say Switch's user base alone will get MP4 to at least 5 million, even without the devs doing anything to try to make the series more popular.

In terms of your ideas:
Open world yes absolutely, I like the idea of having a less linear map, still of course with areas you need specific abilities to reach, and still with some areas that are linear puzzle or battle set pieces.
Don't agree with the adding towns/people or whatever. That goes against the whole Metroid plot so that wouldn't make sense and doesn't fit with Metroid.
Emergent gameplay would of course be welcome, though not sure how this would take shape.
A home for Samus...hard pass. No reason for this at all.
For storytelling I'd rather just have a really good intriguing story that mixes well with the gameplay.

Basically, yeah make the map more open (while keeping some areas inaccessible until powerups are attained) and any addition of emergent gameplay would be welcome but the rest are bad ideas for Metroid.

My pitch would be:
I'd say make the story something like having Samus chasing down enemy, planet hopping where each planet can offer a different environment. This would allow diverse natural environments as well as a mix of civilization environments. Like there could be planets that are composed of ruins, could be all forest environments, going through ice caves, an asteroid mining facility where you're going through tunnels and also the surface of the asteroid as well as abandoned mining buildings, a high tech city run by robots where get to explore interestingly designed robot buildings where you can say shoot out a window and grapple hook to another building and crash through a window and it could also include sci-fi vehicles to hop into, throw in a spaceship level, and so on. I feel like you could really make a grand story with all these environments and chasing down the enemy, while keeping the settings varied and providing some variety of gameplay, and giving the player a great sense of exploration going through all these different planets and whatnot. Make epic boss battles and diverse and really interesting enemy battles. Somehow make the story make sense even though you can go to pretty much any planet whenever you want after say the first one. And then of course market the hell out of it.

I'm honestly unsure if this is supposed to be a legitimate suggestion, or a clever satire piece about how trend chasing homogenizes and ruins everything.

Yeah, the fourth one I was a bit iffy on myself. It’s not necessary, but I think it would be a nice touch. Mostly based around my Zelda experience, and I figured I’d feel the same about Metroid.

The point of my thread is what could be done to increase the appeal so it would be a 20+ million seller. It’s more of a hypothetical of how they could do rather than a post about whether or not it should be attempted.

Other M says "Hello".

While a lot of people kind of hate it, the gameplay was pretty fantastic in my opinion and it made the platforming a lot better than in something like Metroid Prime. Personally, I'd like to see the ability to switch between the Zero Suit (third person) and the Power Suit (first person) so you can make a game that feels like Metroid Prime but put more focus on platforming without it being quite so clunky. 

As for the thread, some games shouldn't be 20mil sellers. The way you make a Metroid game sell 20mil is by making it not Metroid.

Considering OP has consistently used his dislike of Prime in the past to suggest all sorts of things, nah, this is real. 

And its just as terrible as it sounds. 

Also, to suggest Animal Crossing has improvisational gameplay is a big stretch. 

I actually think the idea of getting into vehicles for varied gameplay would have a high appeal. I haven’t played Halo, but I believe there’s something similar in that franchise. Of course, there are the GTA games which have all sorts of different types of vehicles - so it’s not necessarily going to be an alien concept (I know there’s a joke to be made here).

On not being able to pull 10 million. Crazy high expectations for a franchise that’s yet to see 5 million - you might be right.

Word of Mouth is, or YouTube, is key. So the game would have to do things that would make content creators want to show off some of the stuff they’re doing in-game, and also make people who don’t own the game want to watch it. That’s how Breath of the Wild thrived.

While the IP might not have the flagship status, it does have a certain sort of mystique about it, and the status of being one of the franchises from near the dawn of Nintendo’s home console and handheld industries (with Metroid 2). Super Metroid and Metroid Prime are among the top tier most respected games on their platforms, even if they didn’t sell very well. That’s part of why I was thinking the Metroid franchise might be a interesting candidate to Breath of the Wildify - for lack of a better term; or at least it’s the one I’d like to see. I don’t think many thought Zelda could have a game pass 20 million in a few years, and it will very likely pass 30 million. I could be wrong, this is all a mix of the hypothetical and theoretical based on how it happened with Breath of the Wild, and the similarity in the origin of the franchise.

One thing I just thought of with the Metroid’s themselves. Instead of having them all in the final stretch, maybe something more like Metroid 2 where Metroids can be found throughout the game in different metamorphic stages.

I agree, if this game were realistically created, it probably wouldn’t be out any time soon. I’d say much later than 2023, as I doubt Metroid Prime 4 would be made in this style. So at least 5 years - or sometime late Switch 2, or even Switch 3.

This thread isn’t for people who get annoyed about any change from the Prime formula. It’s a discussion about how a Metroid game could reach a much wider appeal than what’s been done so far. A Prime style game doesn’t have wide appeal. A game of that style isn’t going to achieve 20m+ any more than an Ocarina of Time style Zelda was going to achieve Breath of the Wild’s inevitable 30-50 million range.

It’s unfortunate that you don’t seem to understand the difference between formula and IP, but come back any time you’re willing to make a constructive contribution to the topic.

Desolation is literally the point of the series. Removing that is a big reason why Other M sucks. Hunters Sucks. Fed force sucks. MP2 multiplayer sucks.