QuoteAs camera phones improve these high end APS-C systems will eventually disappear.
I guess it should read "high-priced APS-C systems will eventually disappear" ... and that's exactly my opinion too.
Once we get beyond 135mm focal length, lenses for any sensor-size from mFT via APS-C to FF are exactly the same size: "FF size". And below that focal length, lens size and weight does not scale anywhere proporationately to image circle. There's just no point in buying 1000+ € 56mm/1.2 lenses ... unless they cover 36x24mm image circle. :-)
Yes, I meant high priced. If somebody can make a "high end" low priced APS-C system it will certainly be viable.
I'm not saying APS-C will go away, I'm saying APS-C systems that cost as much as better FF systems can't compete and will eventually decline quite a bit in sales. I suppose there will still be a small market for users who care so much about compact size with lots of features, they are willing to pay a big premium for it.