What better way to light a fire under the desktop and tablet CPU industry than the threat of the most lucrative hardware companies in the world shifting to a competing architecture.
Due in part to a stagnant desktop CPU industry, with Intel not facing significant competition from AMD up until just recently, x86 development has been, plainly put, dull. Performance and feature improvements have been minor besides core count increases. The opposite has been true in the mobile and tablet industry, and there's no sign of any slowing down.
Even if Intel manages to drastically improve IPC and efficiency in the shift to 7nm, they would be still be counting on ARM not making further strides ahead given the sheer levels of research, development and demand being funnelled from the smartphone, server, tablet, and soon laptop industry.