let´s look at other factors of dominance, not market cap (which is so easily manipulated, that it does not proof anything).
let´s look at how many goods are bought with bitcoin compared to all other altcoins.
let´s look at how many merchants accept bitcoin compared to all other altcoins.
let´s look what crypto is used for cross border payments.
let´s look how many bitcoin-start-ups are existing compared to all other altcoins.
i bet in every single comparison, bitcoin dominance is still in the 80-90% area.
I think what people aren't really paying attention to is that there are plenty of alts that aim to have nothing to do with any of those services. That being the case they can easily surpass BTC in all metrics.
The main thing that seems to worry people is that alts will take the money that they want to go on BTC instead. Maybe that money isn't interested in it in the slightest. Most of it's chasing more dollars. More dollars were delivered via alts recently.