Rumors of Apple pivoting its MacBooks to ARM processors date back to about 2014. It seems like every year, we're right on the cusp of seeing this fabled product. But assuming the latest rumors are true, it's coming in 2021.
Across the board, companies have been trying to get ARM processors to usurp Intel's dominance for ages. For Microsoft, the first attempt was with the Surface RT and a version of Windows 8 made for ARM called Windows RT. This was a complete and total failure, as every OEM besides Microsoft that announced Windows RT products either scrapped them completely, or discontinued them soon after release.