No reason to believe Sony Ps5 Stock will improve drastically, there is clearly problems at the shipping line at this point, 2021 it is going to be another terrible year for Ps5 stock wise.
Switch will definetely take 2021 it is not even a context.
Ps5 will take the lead 2022 onwards with very very ease but 2021 it is Switch kicking ass in the Top Spot.
Depending on if/when the Switch Pro launches and what it looks like, Switch could win 2022 as well. If it is like New 3ds where only a couple games are really made to use it then it won't, but if it allows for many new games to port over and that incentivizes enough current Switch owners to buy the Switch Pro it could!
At the very least I think 2022 will be close, anything beyond that will be Playstashdomination until Switch 2's second year.