During the Nintendo Q&A session for investors, retiring Nintendo President Tatsumi Kimishima was asked about the reason why Nintendo is expecting to sell 20 million Nintendo Switch consoles this fiscal year (ends March 2019).
In the previous fiscal year which ended on March 31, 2018, Nintendo predicted they would sell 15 million Nintendo Switch consoles within the fiscal year. The estimate was easily met thanks to big titles such as The Legend of Zelda: Breath of the Wild and Super Mario Odyssey.
Kimishima answered the investor that firstly, Nintendo is planning and developing video games targeted at people who have not been playing games recently, and games that people would potentially be interested in.
Secondly, Kimishima said that the ingredients required to achieve the 20 million consoles goal have been put in place. By ingredients, we can safely assume Nintendo already has an idea of the Nintendo Switch titles they are releasing later in 2018, which should all be revealed by E3 2018.