I can’t see Lucid, Rivian, and Tesla starting to go down in market share anytime this decade (short of bankruptcy at least). It is the existing automakers, with a very few exceptions, that are seeing, and will continue to see their market share drop, losing sales to the new companies (which also include BYD and Nio). Ford and GM sales, as an example, have been declining since 2016… at this point down almost 40% from those peaks.
Looking at EV market share in isolation is fairly irrelevant- EVs are now competing with all cars regardless of propulsion system, so the market is all cars.