I'm not sure you can extrapolate that from one company's use of one foundry's process nodes. Intel at least seems to be doing well with their 22 nm process node.
Yep, they seem to be doing well, but they are almost an entire doubling time later if you compare the two previous doublings with to Moore's law.
This might in part be explained by their moving to nonplanar FinFET transistors. And in practice their geometry doesn't quite match the idealized drawings: http://www.eetimes.com/document.asp?doc_id=1261761
Who knows. How can anybody tell if 28nm if more cost effective than 28 nm when it isn't sold in the market as a fab ?