Like I have been saying for a few years now, multiplats of mainstream western titles are and should be the lowest priority for Nintendo.

The main priority is and should be creating an ecosystem where all Nintendo developed/published games can be accessed on a single device rather than split up between two or more devices.

After that, the goal is and should be to accommodate developers who create exclusive titles for Nintendo in order to consolidate the 3rd party support of 3DS+Wii U.

Last on the list is recieving ports of games found on multiple other devices. The vast majority of PS4/XBO software sales come from online shooters, open-world action (or a mix of these two) & annual sports titles and the audiences who primarily play these games is firmly entrenched on the PS/XB ecosystems so fighting head on for these titles is a losing battle.

Best case scenario for mainstream, western multiplat support on Switch is Wii or Wii U year one level of support.

Switch support will most likely look like full support from Nintendo, solid Japanese support, solid indie support, solid family/casual support, and potentially Wii/Wii U year one level of western support.

Doesn't matter if sales indicate a minority crowd in each case. Most of these games were Nintendo-financed and aimed at their own consumers, which are not a specific, homogeneous crowd. That's what I wanted to emphasize when it comes to third-parties and the audience themselves. Most of these games were also profitable, by the way, so the sales expectation per game were met, at least in some cases.

Considering the characteristics of the Switch, I can at least say that the devide will have all the JRPG love in the world. Nintendo consoles already have a huge JRPG userbase for Nintendo's 1st parties and close 3rd parties: Pokemon, Fire Emblem, Xenoblade, Youkai Watch, Monster Hunter... and now that the device has actually enough power to play at least competently some games (in theory Dark Souls 3 runs ok on it, and I'm sure most JRPGs are less demanding than it) a port will make too much sense to them. Hell, if the Switch does REALLY good in Japan, we might see it as the main platform for big JRPGs, and PC and PS4 get Switch ports, but this is in the best possible scenario for the Switch.

Small and medium indies may also try to get into the Switch. Most of them are getting ported to both home consoles, PC, mobile and even Vita, so a Switch port will be routine for them. Specially if they are based on nostalgia and retro stuff, Nintendo fans love that stuff. I still think we'll see a flood of ports from the Vita, at least during the first year.

A-AA western games will probably try the Switch too, because selling a quick portable port of those games will help them. Massive multiplats like CoD, FIFA, AC and the like will probably come too, specially the EA sports. But considering they abandoned the WiiU, I'm not very certain about this.

Other than that, maybe we get a couple of western titles, specially those that have a ton of settings for PC. But this will be the minority. The Switch won't have any major AAA graphics powerhouse that is not a bought exclusivity or a 1st party game.

It could still be cool for many to have their favorite third party games on the go.

I would question the Wii, but yeah. Nintendo offered a great platform for 3rd parties during the NES and SNES, but after them, the evolution and growth of the industry meant that the laws and restrictions that had saved the console industry during the NES were outdated by the time the N64 came (plus home console cartridges), and thus other companies gained the favour of 3rd parties. However, now Nintendo should have a better chance winning back the crowd, at least to a situation between GameCube and GameBoyAdvance (a healthy dose of good 3rd party software that, while not more numerous than the one on the competition, is high quality enough to bring enough attention to the console).

Wii was a goldmine for a lot of third-party games and franchises.

Consoles can't survive on first party titles alone, regardless of who the manufacturer/developer is. Without third party to fill the gaps you end up with big gaps in the release calendar where your userbase grows increasingly impatient.

You may not like to admit it, but it's true, Neither Nintendo, Sony nor Microsoft can be successful on first party alone.

As others already said, I think the switch will se an abundance of JRPGs.
For now, many of those are on the vita but I think switch will take over that role.
And Nintendo 1st party + JRPGs + visual novels (maybe it can in time even get the excellent weird dangan ronpa) does at least to me sound like an interesting proposition

It was surely a goldmine for a lot of third parties, but I would not say that was 3rd party friendly the same way the NES and the SNES were. A lot of companies managed great profits from the Wii, but considering the bulk of the 3rd parties ended up releasing their main projects on the HD twins, I would not say the Wii was that 3rd party friendly. Nobody questions the fact that the Wii had a lot of 3rd party titles, but I would question its importance for 3rd party companies.

I don't know. How many JRPGs are developed with the Vita in mind first and then a PS4 port gets done? Something similar can happen with the Switch. The thing is a handheld after all, and handheld gaming is still stronger there than home console gaming, even with the PS4. Maybe the JRPGs that are more western focused (like FF XV) won't bother on the Switch, but that genre is still full of A-AA (even AAA) titles that would fit on the Switch with little to no efford.