As I said when Hollywood began, back in the mists of time, Hollywood was, I assume, genuinely racist and sexist but my argument is that while modern Hollywood is built upon these racist and sexist foundations it is now just an estate of greed and laziness. This may sound like I'm arguing semantics but to me if we take Hollywood as just sexist and racist then there is nothing we can do about that and we just have to wait until non racist and sexist people come into power in Hollywood. If we take my stance that they are overwhelmingly lazy and greedy instead then there is something we can do about it. Because that can be manipulated and used to our benefit.
Yes it might take time and effort but all it means is that if you want more female leads all you need to do is support the ones they are currently giving us even if you aren't really interested in the plot/ actress/ studio/ etc.
To use an example from a different thread; when Batwoman launches and you want more female leads in superheroes then you need to watch it even if you aren't a fan of Batwoman. Now because one swallow does not make a summer they won't see that as a trend for female superheroes and will assume it is because she is linked to Batman so they will possibly follow up with Red Hood or something but if you avoid that (because it will probably be terrible) they will try to figure out this trend puzzle we have given them and maybe give us Batgirl/ Oracle/ Spoiler. Then they might figure out that people are after female lead superheroes and maybe introduce Bumblebee to Titans which as someone who wants more female led superheroes and people of colour people will thus tune in and support the new trend.
Likewise if you want to see less white, male, leads then don't support them so don't go see Meg this summer even if you are a particular fan of Jason Statham or Sharks, don't go see Meg
As far as Black Panther killing off black superhero movies if the next one lands poorly, I doubt it, same goes for this apparant rumour that they are looking to change lead for the sequel. The amount of money that thing made I would be amazed if people aren't rushing to get another black lead superhero to the screen. This would be a solid swing for getting John Stewart for the next GL movie if he wasn't already. This could be the push Marvel needs to push along that dawdling Blade sequel/ reboot thing they've been talking about. The thing is, a I said, the executives don't watch most of these movies so they are going on guess work. Did Black Panther do well because audiences are hungry for a black lead or was it something else. So to maximise profits they will look at what worked in the past and then pick three or four possible things from it and try them to double check before they chuck a big pile of cash on the next one. You've got to treat them like you're training a puppy. You smack its nose with a rolled up newspaper because it pee'd on the carpet but once won't cut it. You have to reinforce that and keep it up. This is doubly true for movies when they cost so much and are expected to make so much these days.
But, getting back to the original point, I guess that's the difference between you and me. At heart, deep down, I'm an optimist.