They could release a £250 eight core CPU sure, though why would they when 99% of users wouldn't use any more than 2-4 cores?
I was being slightly over the top to illustrate a point (that Intel aren't necessarily holding back on some mythical tech due to their being little competition).
I'll assume your claim of 99% of users not benefiting from more than 4 (never mind 2) cores was made in a similar vein.....