A lot of it will get automated the same way very many industries got automated. A lot of physical labour got automated once a primitive for it was created. Similarly, we have now a primitive for automating knowledge work. In the next few years to a decade, as all the right training data and runtime environments are slowly consolidated for various fields, a lot will be automated. There is no inherent reason a voice actor must be an eternal job, the same way there was no inherent reason for a draftsman or stage musician to be an eternal job.

It has nothing to do with skill. Both were very skilled jobs. Draftsman as well despite many people going to it straight from school. But computers and CAD mean that it is now necessary for someone to do a STEM degree to be a draftsman. Recorded audio made many stage musicians redundant. It is cheaper to do it this way and gets superior results, that is all, there is no further agenda.

Now too, the next generation of voice actors and many other knowledge workers will have to go up the value chain one step and operate or potentially build these tools (in whatever form they mature to in a decades time).

The current generation of voice actors will face the same situation as many before in the performance industry - stage musicians/performers for example that were made redundant by recorded audio. The reality is that most of them just left and dispersed into the economy doing completely unrelated jobs.

For software and generally computer engineers, this new primitive happens to itself be software, so it's less of a transition and an easier upskilling path to learn to build it. And building it is one step higher in the value chain than simply using it. That is a structural advantage.