I find it really depends on where you live or who you're working for. Here in Canada (Ontario specifically), it's a pretty big deal given that some organizations have to hit accessibility requirements on their sites if they have certain characteristics (number of employees etc.).

It's led to a good percentage of the work done here (both in traditional CMS implementations to custom applications) require accessibility not as an after thought, but baked in by default.

Makes it better for everyone, but without a good handle on what it actually means, and ensuring that whatever toolsets you're using (CMS, JS/CSS/backend framework, library etc.) also provide the necessary tooling as well, it can make projects run over time/budget.

Factor that in first, learn the tech/tools, and it doesn't have to be that dramatic. I'm assuming that common accessibility on the web/mobile will be expected nearly everywhere "soon".