Hmmm, how did I miss this thread. I'm sure I put some numbers in a separate thread at some point.
Take my prediction knowing that it was given on 10/30/2017 when Switch was proven success and Nintendo up'd their supply statements once since launch.
I bet that they'll have a solid Q4 and reach 13MM by 3/31/18.
To put this into perspective, Wii sold ~18MM in its "first year", but that year included 2 holiday time periods since it launched in November. Switch will only have had one.