SuperData expects Nintendo's Switch console to finish the year with 5 million units sold, but a lack of compelling software in its early months will likely result in a slow start.
http://www.gamesindustry.biz/articles/2017-03-02-nintendo-switch-to-sell-5-million-in-2017-superdata
IHS Markit has forecasted the Nintendo Switch will sell 4.4m units by the end of 2017, with the vast majority of buyers being either existing Nintendo console or handheld owners or general early adopters.
http://www.mcvuk.com/news/read/ihs-switch-to-hit-4-4m-sales-by-end-of-2017/0179624
Quite hilarious because 4 months after launch Switch is at 4.7m with huge stock issues, and we still have 6 months of sales including holiday season. :)