Unfortunately for professional voice actors, they have have lost before the fight began. Current generated voices are highly limited, unable to fully replace a human voice actor but they can replace a lot of mundane NPC game dialog speech. However, the mere ability to make voice A sounds like voice B means that it only requires a single talented voice actor to play every part. While not trivial, progress will be made to identify and replicate someone's cadence, pronunciation/accent, voice stress and other subtle factors that could make an ordinary person be able to play every part. It will come to the point where you'll be able to record your voice and will be converted into a format that can be edited with ease, changing every aspect of it which is when voice acting truly dies.
I love voice actors because they bring animations to life but their profession has become a dead end because it's merely possible to not need them. They may win concessions using a strike but it will push the development of this technology harder and faster.
The same process of replacement is slowly happening with every aspect of game and film development because capitalism self-optimizes for cost without regard to anything else.