How long have you had them?
When our first ex-batts arrived, we had the odd shell-less egg and soft-shelled egg (these birds didn't look bad at all to start with, not too many feathers missing). We fed them crushed egg shell which seemed to do the trick. They went through a time of not laying much, and someone else's ex-batts birds didn't lay for their first month, but it's an 75% laying rate again at the moment.
Ex-batts aren't rehomed once they stop laying, they're rehomed after a certain time because their laying rate is expected to go down after about the first year from around 95% to 70-80% (or something like that, exact figures not at hand at the moment) and then less again the following years.
If chickens had bronchitis, would they be bright and happy like yours are?

Even if they don't lay anymore but you want to keep them since they're as pets to you, then why not? There are more expensive pets to be had than chickens

I'd do the culling for you if you lived closer by but I'm down South
