I picked the 26.0-27.9m range. We are just a week away from 2019's Lite launch for year over year comparisons, so 2020 will lose a few hundredthousand units over the course of the first three Lite weeks. Afterwards 2020 will make it back and then some, but this year's holiday lineup lacks the system seller that all previous years had. 27.5m-27.9m is what I expect, but it's not far from there to slip into the 28.0-29.9m range.
For a confident 28m+ vote, Nintendo would have to have a bigger exclusive than Bravely Default II or New Pokémon Snap left to give a 2020 release date. The next tier of 30m+ is the one where it's already unlikely that the production is at a level where such a number is possible.
In any case, the remainder of 2020 will be up year over year, but not anywhere close to the same levels as the 2020 period that is already behind us. In 2020 there's no launch of a new model nor a strong holiday lineup, so what will cause the remainder of 2020 to be up year over year regardless is the strong momentum that it has built before going into the remaining stretch of the year.