It makes sense for the big cloud players to start working on real 64 bit ARM options. The vast majority of AWS Linux micro instances could be capably serviced by a modern ARM CPU at greater densities than Intel can deliver.
HP have already shown off the density possibilities via Moonshot (albeit as "enterprise" grade ARM kit, with a lot of unnecessary guff wrapped around it and only on 32bit). Give someone who builds their own hardware and platform by cutting unnecessary components (i.e. Amazon, google, facebook) and I bet they could cram a LOT of very usable low end compute into a very DC cost effective footprint.
Red Hat have shown off RHEL running on ARM64 now, so ARM servers are certainly coming. I don't expect them to replace x86 an AWS or anywhere else any time soon for many users, but it'd be a great start to diversifying the platform. Good luck to them - them working on diversifying one of the few areas (x86 based servers) in which there is currently no real alternative to the industry standard can only benefit us all in the long term.