Well, Intel will only allow its fabs to companies that do not hurt its bread and butter. Its current disclosed clientele of Altera (FPGA), Netronome (networking) and Cisco (networking) do not compete with Intel's MPU/CPU/SOC (yet) and hence will bring only rewards and little risk.
Any ARM based SOC manufacturer will be a non-starter unless Intel specifically choses someone so as to provide them a leg-up.
Right now Intel's competitor (per Intel's own words a year/two back) is not AMD but Qualcomm. And to answer their paranoia, the market cap of QCM and Intel are now comparable (betn Nov12 to Mar13 there were times that QCM was valued more). So if Intel is unable to get anywhere in mobile x86 and it wants to screw Qualcomm, only then it will allow a QCM competitor to fab chips at its fabs..