If Nintendo makes a console that can accommodate the needs of all parties, the only thing stopping it from selling would be controllers and user loyalty. Having Nintendo and all 3rd party support would be Nintendo's comeback. but what decides a comeback is if the crowd is willing to leave PS or XB in favor of Nintendo.... but I doubt that'll happen. Nintendo succeeds in doing something different and new with their hardware. That's where their strength is. If there were to simply mimic the other 2 VERY similar consoles, somebody would have to drop out.

With that being said, I always have this dream E3 in my head where Sony has a press conference for their next console and first they start off playing Uncharted or something Sony on the PS5 and then Reggie comes up on stage and presses the eject button and puts in the newest Zelda game and starts playing. Nintendo moves to 3rd party announcement...that would be...so epic. But Nintendo is already making a new console so those dreams will stay dreams.

But, overall, "comeback" isn't defined by XB and PS's success. Nintendo doesn't need a 100M selling console all the time to stay afloat. They've done that with Gamecube and 64. They simply only need to make profit. Their handheld line is more than making up for their console woes and people don't want to point that out. The only thing I'm saying is, don't EVER underestimate Nintendo. When they find that gold, they mine the hell out of it. With their push to mobile, with their IP and game making finesse, I think that's what they're about to do. Mine the hell out of mobile.

In the end everything dies, even Earth minus Nintendo.

They survived the Wii, so yes.

Of course they will...

I doubt both of them can survive the 9th gen even if nintendo drops out today. It won't take long for people to realize how much better the PC is.

That couldn't be more correct. Bullseye, that's the point. However, I do believe they can survive in a more niche position (in home consoles, not talking about portables here).

Buy a game

Check to see if you have the minimum or recommended requirements for said game.  If not, spend money

Install It 

Try to Run It

Go around updating Drivers because said new game doesn't run

Run the game

Runs terribly

Mess about with set up, graphics options, resolution

Finally play game ( or dont play it, but tell everyone within earshot how amazing it runs regardless)

Or

Buy game, play game.

There is a reason consoles are more in favour regardless of whether they fall behind the PC in terms of specs or not.  Plug into TV, buy game, play away, on a closed ecosystem with friends.  Thats all you need to do.

Everyone was fine last gen weren't they?

Buy game, installs in 2 minutes (PS4 anyway) automatically downloads any updates (does whilst playing most of the time) play. 

Still far more simple. 

As a life-long Nintendo fan, it's hard to admit that Nintendo, in it's current form, probably won't ever be a dominant force in the home console space again. Nintendo just doesn't see eye to eye with third party developers and publishers, both on hardware and on business. Nintendo wants 3rd party publishers to approach them, on their terms, with whatever hardware Nintendo wants to make, while Microsoft and Sony both them instead. Nintendo makes hardware to fit their software, because it gives much greater freedom to craft their games. It's what gives Nintendo's games their "Nintendo Magic," but it sometimes comes at the expense of 3rd party developers. Nintendo's way isn't wrong, it's just different.

With Nintendo being unwlillng to compromise in any meaningful way, and it's competitors aggressively seeking 3rd party support, and being willing to come to a compromise on HW features and cost, I don't believe they have a chance. It's like seeing an immovable object meet an unstoppable force. It'd be cool if it happened, but it isn't going to happen, because it's not possible.