True, Bitcoin today enjoys a 91% market share of crypto. However, in the overall scope of a USD $7B asset class adrift in a many-$T sea, that market share is not unassailable. Indeed, should the masses finally decide to adopt crypto, I would expect them to adopt one that they can actually _use_, rather than one that prevents them from participating due to an arbitrary limitation. Any of dozens of shitcoins are waiting in the wings to meet this market need, jealously awaiting a chance to procure adoption by delivering real value in comparison to Bitcoin.
IOW, you have an inaccurate picture of the competitive marketplace.
And if you think miners would not switch in a second to some other coin, should it deliver larger profits, you are delusional.