Market share in the EV market is complicated by determining what kind of EV is being discussed. The kinds of EVs include BEV (Battery Electric Vehicles...these are the 100% electric EVs which don't have any gas engine or hydrogen fuel cell to complement the battery), HEV (Hybrid EV...these have gas engines that create the electricity that charges the EV battery and runs the electric motor), PHEV (plug in HEV...these allow you to plug in to charge the battery so that you don't need gas to charge it), and FCEV (hydrogen Fuel Cell EVs...these are discussed here.)
When discussing Tesla Market share you are talking about BEV with PHEV sometimes included . The following charts give some examples of mid 2023 market share info.
One month of sales worldwide broken down by car model. Note that plug in hybrids are included as well.
As other car companies slowly catch up in production and increase their BEVs demand Tesla will lose Market Share. Prices will also drop as competition increases. This will be complicated by many cars dealership model as well as their need for new factories and increased software and electrical engineering expertise.
The following charts show this evolution in more detail.
As you can see, globally Market Share is leveling out quicker as China pushes out less expensive models,,,with some less than $4,000 making the term market share a bit misleading...more so when many car companies sell BEVs for a loss. At time of this edit, the following is the most up to date quarter for US sales: