Call me crazy, but I think the Switch Pro is still coming, just next year, not this one. The OLED model is a half step and will replace the base model, while the actual Switch Pro launches in 2022. Basically a 3DS XL model vs a New 3DS model. Nintendo has shown that they are more than happy to release multiple revision within a single generation. Between that 'Pro' revision and the heavy hitting games that year (plus the chip shortage being hopefully resolved) we should hit 30 million.
Now, this does hinge on a couple of things: first that the chip shortage eventually catches up to Nintendo this year and prevents them from tracking too far ahead of 2020. Secondly, that the new dock contains the technology to allow 4K upscaling that the Switch Pro is rumored to get. The old dock, if I understand it correctly, doesn't have the ability to handle 4K bandwidth, even only upscaling rather than native 4K. Data miners found references to upscaling in Nintendo firmware which makes me think Nintendo is setting the stage for stronger revision.
But I will confess, this could be more hopeful conjecture than well-founded argument since I definitely want a Switch Pro.