Splatoon finally marks Nintendo's entry into the online shooter space, I think we'd all probably agree that they should have done this a lot sooner. 

What other genres should Nintendo be looking at? The mideval/fantasy open world game? Yes they have Zelda, but things like Morrowwind and Witcher III seem to be all the rage right now, maybe a new IP in that genre would be a good way to go. MMORPGs perhaps?

I think more multiplayer "crowd pleaser" type games are things Nintendo should look at too ... another multiplayer FPS besides Splatoon should be a target. I really like the idea of re-aquiring the available James Bond license, but even something original would be great. 

Too many 2D platformers in Nintendo's fold right now, not enough shooters, fantasy open world games, and sports games. 

I think Nintendo could pull unique twists on genres, like they did with Splatoon and the shooter genre, and make a hit out of it.

Of course, they should still continue to focus on the games and genres that defines what makes Nintendo Nintendo.

If they cover Sports, I'll be satisfied

they should but they cant. too many IPs.

I would like to see a Mario Golf, Mario Tennis, and Mario Strikers game on the Wii U. 

I think Nintendo need 3D platformer besides Mario 3D World, something similar like Banjo Kazooie or DK 64.

They probably could but honestly it would probably mean scaling back some of their other games. 

As much as I personally like some of these games ... Nintendo totally is over-invested in "weird/nichey Japanese games that don't even sell in Japan".

See: Bayonetta 2, Wonderful 101, Sin & Punishment, Devil's Third, Fatal Frame, gulp yes even Xenoblade etc. 

They'd be better off investing in genre types that are more popular in the West I think, even what's left of the console audience in Japan seems to prefer that. 

Also way too many 2D games ... Mario Maker, ok, at least that's bringing something new and sure to sell, but DKC, Kirby, Yoshi, on top of NSMB/NSLU was overkill. 

I give Nintendo credit for finally looking around at what people were having fun playing elsewhere and understanding that they can borrow something from that while still being creative.

However, it did take longer than it should have. I've been saying for a long time that Nintendo should pay attention to the rest of the gaming world and I've had people tell me that I was wrong. I doubt anyone who likes Splatoon will tell me that I'm wrong now.

If Nintendo tries to roll into next generation solely on the backs of Mario and company then they will once again have trouble attracting new users. Right now, with the Wii U, they should be trying to find new talent inside their studios. They need to build as many new IP as possible that offer something new while still providing proven game-play experiences.

This is a great chance, to be honest. Throw stuff out, do some brainstorming, see if anything sticks. Explore other games, see if there is anything they can learn. It's not like they're going to harm the Wii U by using it as an experimental platform.

I am not sure how much more room there is in the market for Nintendo to 'Spletoon' other genres. They have had some success with sports games (Mario Strikers, the Mario baseball game, etc.), but nothing huge. They are already represented well in many other genres so I don't see any obvious crossover openings in the same way as Splatoon.

I do hope Splatoon is a huge success however, both to show Nintendo that there are rewards to be had if they go into competitive markets as long as they deliver a quality experience and to show other developers that there is a market for great experiences on the Wii U as well.

Possibly, but I'm fine with Splatoon being the only Nintendo shooter for now.

I'd like to see more Fantasy, Open World, and JRPGs though