Yeah I think that's the range as well.
LTD is going to be an absurd total, among the best ever for 1P-focused games.
2M to close out this year puts it at ~4.9M for the calendar year, basically flat from 2018, and sitting at ~16.5M total. Greater than 2M results in an increase for Cal 18 > 19.
Even a 25% YoY in 2020 gets it over 20M by the end of the year. More promotions and/or BOTW2 marketing cycle can boost it as well (think a direct sequel is more likely to boost it, not hamper it), depending on when it releases.
I think it's got its sights set on >25M LTD, maybe closer to 30M. And then 1.61M from the Wii U version as gravy on top of that.
Also BOTW2's launch perf is going to be almost at Pokemon/Smash levels with this kind of WOM for the first. In the US it could be higher.