They're using TSMC out of necessity, not desire. Intel's fabs are integral not only to their success and profits, but to the infrastructure of the United States itself. We simply cannot allow all CPU fabrication to be offshored, especially when most of it is close to China (Taiwan / TSMC). Samsung is too busy pumping out smartphone / tablet CPUs and NVIDIA's GPUs, so even if Intel wanted to use them, there's not enough capacity.
Intel is going to have to get their shit together, not just for their own sake, but for strategic manufacturing security interests of the United States as well.
Given the expensive involved in bleeding edge manufacturing and the comparatively low volumes of sales, the consolidation of manufacturing capacity is not really surprising.
It makes much more sense for them to focus on making content than making ARM chips.