You are just talking Switch exclusive line-up right? If so then I'm curious just how many more games you think we're gonna get if 8 titles still isn't most of the line-up. In 2017 we had I think 8 games (BotW/MK8D/ARMS/Splat2/M+R/FE Warriors/SMO/X2) then 12 games in 2018 (Bayo2/Kirby/Labo1/HW/DKCTF/MT Aces/Toad/Octopath/Labo2/SMP/Let's Go/SSBU).

2019. will most likely have more exclusive releases than 2018. had, I will correct my self a little with points that you mentioned, IMO we have around half of 2019. confirmed exclusive games (if 2018. had 12. I see 2019. at least around 15), like I wrote, expecting at least 2-3 more new 1st party games, 1-3 more Wii U ports and 1-2 3rd more party exclusives.

I think 2019 could surpass both 2018 and 2017 combined in terms of original games and quantity of games Nintendo publishes. Nintendo published more Switch games this year than 2017, but they released bigger titles in 2017 than this year. Aside from Smash, nothing this year really reached the hype and anticipation of BotW or Mario Odyssey. 2019 is when the Switch is looking to be when the merger of home console and handheld resources really comes into fruition. No offense, But I personally think your list is a little too conservative. Then again, mine may not be that realistic either. 

I'd expect 12-16 first-party games, given Nintendo's output so far on Switch. We can possibly add Skyward Sword HD to the 2019 list - Aonuma has apparently teased it to Zelda concert goers in Japan.

Reports from Japan suggest Aonuma teased Skyward Sword HD at a recent Legend of Zelda music concert. Unconfirmed reports, mind, but Japanese Twitter lit up with people saying the same thing.