Yes, I'm very certain that it wont fall behind launches aligned. They look to have a steady stream of games coming in 2019 that will maintain and grow its lead over the 3DS to an amount that the 3DS wont be able to come back from. No doubt about it.
Wii U faced its demise because of two things:
1) Nintendos own mistakes. Very little marketing (and the marketing that was there was very poor). A lot of my friend circle were left thinking that this is some tablet add on to the original wii. The system launched without a good killer app (2d mario clearly didnt cut it), and had a huge software drought in 2013 especially. There wouldnt be a must-own game until Mario 3D World, which came out a few years. The whole gamepad gimmick sucked as well.
2) Mobile gaming taking over the casual market that Nintendo was going for. Why buy a seperate device when the device you already have has 100's of games beforehand?
Lets say if Nintendo actually spent some marketing dollars, called it Wii 2, took more care of the software situation with a steady stream of titles, etc, some third party support wouldve arrived as a byproduct, and the Wii 2 would've sold 50 million units (still only half the wii due to Mobile gaming)
No it wouldn't.
N64 and GC didn't had droughts, they had competent HW and also were marketed and priced right.
It is purely speculation and wishful thinking. In real world if you look Nintendo had only been dropping on console world NES>SNES>N64>GC>WiiU ... Wii sales were mostly from non-gaming public. If Nintendo was able to sell 80M HH plus 50M consoles per gen why would they make the hybrid and cut themselves to a single market that will do around 80-100M?
The answer is quite simple. They wouldn't. Nintendo knows they couldn't compete directly with Sony on the home console market without a gimmick/hook. The Wii succeeded in hooking in the more casual market with its motion controls, which helped it thrive for 3 years or so. However, the novelty started to wear off, and a console many thought was destined to rival the PS2 ended up having to crawl its way across the 100M mark. The PS3, Sony's worst selling home console, only sold ~15M less than it.
The Wii U was an attempt to recapture the exact magic of the Wii. HW that was only slightly more powerful than the previous gen, a gimmick controller (this time trying to appeal to the growing number of phone/tablet gamers), and a price point lower than the competition. Unfortunately for Nintendo, those casuals were just fine continuing to play on their mobile devices. And the system was as pointless to the more core audience, as they were ready for an actual tech jump from their PS3s and 360s. Nothing was going to change the outcome the Wii U saw.
So, Nintendo, realizing it couldn't compete head to head in the home console space decided to combine the market with one they were much stronger in, the handheld market. Combining the two, they were able to appeal to the handheld gamer, while also having some presence in the home. It's an approach that really suits them, while also seemingly allowing the PS4 and Switch to really have no effect on one another. I think its the model they will continue to adopt, while Sony continues as a sole home console that strives to have a good price to performance balance.