> How long will it be between the introduction of lab-grown meat until killing animals for food is banned? Is this a generational thing (so older people still consider eating animals to be acceptable, while younger people do not), or is it a country-wide thing (countries move to ban eating animals one by one, driven by a general shift in moral attitude), or what? How does this change in morality propagate through society?

Just because they ate meat? Maybe not, but they may not look kindly on those that did large scale killing with less than humane practices. I could see this individuals being more likely to be "Cancelled."

Maybe those that fought vegans or fought against animal rights activities?

Those opposing change for the better or were active participants in things we in the future see as bad.

Remember that most people cancelled were active participants, rather than passive bystanders going with the flow.