Your "less than 2M" prediction for the PlayStation's third-party software sales in 2021 is way too aggressive IMO.
The issue is that compared to last year there would be a lot more Switch titles in the Top 1000, and a lot less on the PS4/PS5. So far the "major" titles on the PS4/PS5 that have a launch date are Village, Nier Replicant, Scarlet Nexus, Lost Judgement, Tails of Arise - combined it doesn't seem that they would be able to surpass 1 million units.
Based on E3, I might bump them up a bit. Since I'm basing the decline on what we know so far.