Not entirely true as I'd say that void for that branch of FPS games was filled by Prime as the Prime series is technically the successor to the Turok series both having similar approaches and sharing the same team of people behind them (Retro were the Turok team) only difference is that Turok is more of a shooter. In the case Goldeneye and Perfect Dark that branch of FPS is done they raised the bar back then but the likes of Halo raised it to a new standard.

Retro could be working on something more western like but imo it doesn't have to be a FPS per say I'd say they need something more along the lines of what Naughty Dog puts out as tbh people wouldn't really go to Nintendo for a FPS but they'd likely go to them if they had their own western like titles similar to what companies like ND and Bioware put out.

Pardon but NOTHING on the GameCube had a "ton" of hype.  Well, except Twilight Princess.  Mainly because the GameCube's marketing was so awful and just plain forgetable.  As in, I can literally remember not a single ad. 

And also worth noting that past sales are not necessarily indicative of future sales.  The Elder Scrolls is the ultimate example of this, going from being niche to selling almost 4 million to selling over 8 million to selling over 20 million.  You can't just say, "x series usually sells y, therefore x series will always sell y".  Far, far, far, FAR too many variables. 

In my honest opinion, Prime has never hit its sales potential.  Not once.  The marketing has been minimal to non-existent being the most obvious point.  The big difference now though is how the market has changed.  Exploration is a much more popular thing. SciFi is bigger now than it has ever been.  The Nintendo brand is looking far healthier than it did in the GameCube era.  Nintendo's marketing has been on point and they have put significant effort into promoting every single first party effort at retail.  I'm not saying Metroid Prime 4 will sell 10 million, that's just nonsense, but if all these things stay their course, it could be the best selling Metroid in my honest opinion.  Of course, a lot of this is dependent on what the game is like as well. 

But no Prime is not as big as Mario.  However it could move systems mainly because it will be different from prior launches, adding diversity to the lineup that will appeal to people who are on the fence.

Really?  More reasons to not like the Splatoon series in addition to the lack of local split screen and its terribly annoying aesthetic.

Nope keep multiplayer far away from metroid

To be honest Nintendo needs more multiplayer IP in general.

Splatoon, Mario Kart, and Smash Bros. have done so well, and this is not anything new, GoldenEye/Perfect Dark/Turok on the N64 ... Nintendo makes way too many single player centric franchises when their buyer base generally has a strong preference towards multiplayer fun.

They never should've stopped making FPS shooters even if Rare was sold. Something like Nintendo's take on Overwatch would've sold a lot more than ARMS I think.

I'd say the big hitters will likely be Animal Crossing and New Super Mario Bros 3. Animal Crossing is overdue for a new game, and 2D Mario in some form is still a heavy hitter. I'd say that a new Mario Maker would be more likely, except that doesn't work well for the Switch's strengths.

Not touching on most of this but XENOBLADE. IS. FIRST. PARTY.  It's as first party as Mario.  Monolith was bought by Nintendo and began working on a new, Nintendo owned IP called Monado: the Beginning of the World.  The IP was then renamed to Xenoblade Chronicles.  It is a Nintendo first party IP.

But I will go ahead and agree that Nintendo already has a good number of multiplayer experiences.  A couple more would be fine, but singleplayer has immense market potential still. Not that I wouldn't mind seeing Nintendo try their hand at a shooter or realistic racer.

Hyrule: Souls of Sages

Made by From Software.

It's a Souls game but rated T. It take splace in the great war mentioned in LTTP. You play a unamed Hyrule Soldier who must free the sages. They have been taken over by the corruption of evil. You must defeat and free each sage before the ultimate evil is reborn and takes over Hyrule.

did you all forget that Nintendo stated they were going to release an animal tossing game in 2018, I don't think there will be a Switch animal crossing that year. Hope it's Smash and luigis mansion or something

mii party + animal crossing
pokemon i think is 2019, metroid 2020.