For what it’s worth, I have had at least one hen the last few years with a bottom like the one in your pictures, and they tend to live fairly normal lives for a couple of years, although they haven’t laid eggs. Every hen is different, as @coach pointed out, the enlarged lower abdomen can be from different issues. I watch for bullying or any suffering, and I usually put them down and do a necropsy to see what was wrong. Usually when one is on the way out, the others may start pecking their combs bloody, and I separate them or put them down. I know how to drain a hen with ascites, but I chose not to, since it is only a temporary fic, but also can potentially cause harm.