Apple needs x86 to run existing apps. Who would accept a a big slow down for a slightly cheaper laptop. x86 intel chips are a RISC design with a glue layer which grafts x86 on the outside. Could Apple design an x86 chip with an ARM RISC core hidden inside? Sounds pretty complicated, I doubt they have a big enough hardware engineering team. If there was an ARM core inside could it be exposed for recompiled software to take advantage of it? Big issues managing state/contention between 2 different ISAs?