Piper Jaffray analyst Gus Richard doesn't see it happening until 2015.
"We believe Apple could add roughly $5B-$6B/yr in revenue for Intel but is unlikely to be a foundry customer this year or next," said Richard, who follows Intel closely, in a research note today.
Even the Intel bashers won't rule it out -
Apple is still 100% depending on Samsung - even over the next couple years but Samsung is not considered by Apple for 20nm (at least to my knowledge).
So while Samsung is being phased out Intel might be being phased in.
The 2015 time line is very similar with ALTR.
As far as I understand Apple is not using ARM for GPU.
Paul O once mentioned that both Intel and Apple have in common laying out a "good" portion of the design "by hand".
Maybe they can merge an x86design with Apple GPU.