Obviously a 40% increase was not plenty, or this wouldn’t be a problem. For example, I wouldn’t take a 40% pay increase to be constantly on call. A 200% increase, yes I would do that. So there is a number for me, I’m just not sure exactly what it is.
There will always be people who refuse at any price, but you don’t need to convince everyone. You just need enough captains to keep scheduled flights from being cancelled. There’s a number that gets you there, and the only thin we know for sure is that it’s more than 40%.
Fwiw I’m not disagreeing with your first point. Reducing the demand on captains could also help.