Once they realize that it doesn't replace senior but can easily replace junior, junior dev will have a bigger problem and the industry at large will have a huge problem in 8 years because the concept of "senior" would have vanished.
I consider 8 years to be the real experience to be considered a senior dev.
If from now on, the amount of junior is drastically reduced, this will lead to a lack of senior in 8 years because the senior leaving should be the same proportion.
In a situation where they replace juniors with agents, yes, we'll still be senior, but just like people capable of setting a VHS recorder, our number will dwindle.