I don't know if the prospect of being the "Intel of ARM" is very appealing when you can manufacture high-margin smartphone SOCs instead. The addressable market doesn't seem to be very large; any potential competition is stifled by licensing on both Microsoft and Softbank's side.

The legend of Windows on ARM is decades old, and people have been seriously trying to make it happen for at least the past two decades. They're all bled dry. Apple is the only one who can turn a profit, courtesy of their sweetheart deal with Masayoshi Son.