I think A, B and C will coexist.
I think B will go eventually too but as its pretty uncommon I am not bothered by it like I am Micro and Mini USB which need to go ASAP!
Also, lightening has had its time, not that it was bad, it just is time to phase out.
As others had said, there is no rush to replace A with C, this would create way too much e-waste. (USB Micro and Mini devices are e-waste already due to the flimsy ports)