2019 is looking to be the year the Switch really starts feeling like an evolution of Nintendo handhelds. Many 3DS series and games associated with handhelds like Pokemon and Animal Crossing are on their way next year, this time developed with console sensibilities in mind. Third party support is looking to go full steam ahead with more multiplatform titles releasing in a closer time frame to the other versions, plus an increase in more unique exclusives like Town, Ninjala, and Daemon X Machina.
Perhaps what I'm most excited for, if it happens, is an increase in more experimental games from Nintendo. For the most part, many of Nintendo's Switch games were planned prior to the console's launch, with the bulk of them being in 2017. 2018 had more games, but not as many interesting ones, and a lack of digital games like Snipperclips though is a bit disappointing this year. I fully expect this to change next year, as I think we'll see a bigger influx of new IP and niche titles along the lines of ARMS and Labo.
The biggest thing about the Switch next year, is that it won't just feel like a Nintendo handheld, but it'll feel even better than that.
For me the Switch always felt like a Sony handheld with additional Nintendo games... and that is a good thing.
The Switch seems to me like a spiritual successor of PSP and Vita with many similarities and with some additional Wii genes (motion control option of the Joy-Cons).