They will do a speech discrimination test. If you score highly with hearing aids especially when not lipreading then they are likely not to recommend you for a CI. It involves surgery and is expensive so that is why they aren't in a hurry to do it for everyone.
After the sudden increase in my hearing loss I got 0% with hearing aids without lipreading, about 90% with hearing aids and lipreading and about 50% with just lipreading. My audiologist said this was good as it indicated my brain used sound to discriminate speech but that my hearing aids weren't providing much to me.
R2D2