I think a few distinctions need to be made, between a private business making a decision regarding an employee and twitter mobs.
I assume both Kaepernick and Carano were aware their actions would have consequences, as they did. If they weren't, then they are just naive or were ill-advised. I don't think either case is cancel culture, it's two businesses making a decision they thought (rightly or wrongly so) was good for their business. Are they the same? I don't think so and with time everyone clearly sees the difference. Kaepernick, years later is being applauded for what he did and most people recognize it was a bad and unfair move on the part of the NFL. I don't think in 5 or 6 years anyone will be looking at Carano as some sort of leader for free speech or something like that. She said offensive stuff and paid the price. Kaepernick stood up for something most consider fair and paid for it, unfairly in my opinion. Others will think differently.
Neither the NFL nor Disney give two shits about police violence or free speech, they act according to what they perceive to be the public opinion amongst those who pay for their products. So their actions will be determined by, ultimately, the community. And in time, unfair things will self-correct. Kaepernick is now widely applauded with even the NFL admitting their mistake. Will Carano be back and forgiven? It will mostly depend on her, although early signs show she preferred the rabbit hole. If she returns, it will be because the community has widely forgiven her.
What the hell am I trying to say? These actions are determined by the community and what the community accepts as fair or unfair at any given time. If you say stuff or do stuff most people in the community regard as negative, you will pay a price, not because you're being canceled but because you have a weak product in the marketplace of ideas. This has happened since forever, it's nothing new. It's not a conspiracy, it's not an ideology trying to destroy you, it's a result of societal evolution and some people failing to adapt. Society doesn't all move at the same pace, so sometimes you will have cases like Kaepernick and it's unfortunate but inevitable. As society moves in a certain direction, these people will be vindicated and celebrated or will fall into obscurity.
Regarding twitter mobs, we have two different thing.
Hashtags wanting to boycott someone and pressuring a person or an entity are perfectly fine. One million people going to the amazon twitter spamming them with "providing better working conditions or I'll never buy from you again is fine", a million people spamming Manchin's twitter telling him to vote for whatever in the senate or they'll kick him out of office is fine, a million people spamming Downey Jr's twitter with "if you keep defending Mel Gibson I'll never watch one your films again" is fine. It's not cancel culture, it's the community applying pressure on people and organizations so that something they believe needs to change actually changes.
Now a million people twitting "I know where you live" or "I'll do this and that to you", that's obviously unacceptable. Is it cancel culture? No, because ultimately that person will have their voice heard on other platforms depending on if those platforms will take something from those people (wether it's profit or credibility). People who are dicks online and threat people are always in the minority, sometimes it'll seem they are the majority because they are very vocal but organizations will not make decisions based on this minority, they can see where the majority of the community is going and they will follow (sometimes the silent majority and the dickhead minority want the same thing but companies will decide based ont he majority always). So if what you're saying if valuable to the community, it doesn't matter how many threats you get online, someone will give you a platform for what you're saying or doing if there is a space in the community for that. It's not a coincidence that people who cry about being cancelled invariably find different gigs at different places, so they're not really cancelled, are they?
Anyway I've written too much, sorry about that.