I don’t think anyone disputes Tesla are No1 at the moment but the tech is not something that others can’t match quite soon now they release their funding brakes into the EV market.
My point is cars are quite personal and people like to have a car that feels unique even if many have them. Example being I have never bought a Ford as they just feel boring. The market needs many competitors to offer different styles etc and 1 dominant would be a dull car.
That’s not to say it won’t be a market leader but it’s price as being worth more than many competitors combined I think will change. That could be others increasing value rather than Tesla decreasing but market value % I believe will level off.