Can't say I'd be too surprised if we got something like a Switch Mini soon, considering we got Game Boy Micro after the DS released, New 2DS XL after the Switch released and Wii mini after Wii U released. We'll see what happens with this rumor.
I don't see a Switch Mini being what pushes the Switch to 160m total. I still feel like it would end off around 150m assuming the successor does indeed launch next year.