Replacing an already very successful OS with a rewritten one, including a completely new kernel -- that would fundamentally break backward compatibility. And therefore it simply doesn't happen.
Only Apple could perhaps pull that off by forcing it on everyone by way of controlling the hardware base. Google and Microsoft don't have that amount of control.
Only Apple could perhaps pull that off by forcing it on everyone by way of controlling the hardware base. Google and Microsoft don't have that amount of control.