Hi , the chemo and abiriterone do different things so I don't think use of one excludes the other.
Chemo kills the cancer (and anything else fast growing). If it does not work it's usually because the man can not cope with the "poison" I've has a reaction or it damages too much else along the way, that is rare but does happen, 80% of men do well on early chemo.
The abiriterone I believe stops the cancer cells increasing in size by blocking the "food" source for a while.
So the chemo shrinks the cancer( my tumors went from 3.5cm to 0.5 cm on chemo, zoladex and biclutamide). Then in my case the cancer got clever and started using biclutamide as food so they stopped that, then as the PSA kept rising they started me on abiriterone. So for now I would imagine they don't reach for the abiriterone for your hubby as they will want to see if the PSA falls with zoladex and biclutamide first, then I would guess chemo soon and then wait. From what I understand you want to save the abiriterone until as late as possible if the other stuff can bash the cancer without it. Abiriterone does not work for everyone, you will know shortly after it starts if it does, my onco said average success is 18 months, some not at all some 4 years. Every mans cancer is different so like you when we look for answers we could be at the top or bottom of the spectrum or where the majority sit, in the middle!
As ever caveat that the above is what I have gleaned or been told by my onco , I am no doc.