Seems like ARMv8 + SVE could provide some decent competition for the Xeon Phi. In a way both are heirs to the IBM blue gene line (lots of low power cores) and "old-school" long vector systems like old Crays or NEC SX.
Interesting times.
Interesting times.
While Phi are easy to port, they aren't close to GPUs for vectorization-friendly problems. This is likely why the Aurora supercomputer has been delayed/canceled.
IIRC Andy Glew had some slide deck where he advocated that. Edit: https://drive.google.com/file/d/0B5qTWL2s3LcQNGE3NWI4NzQtNTB...
AVX-512 has many of the primitives required, and ISPC ports the GPU programming model to CPU SIMD.
For buying a machine, it depends on what you want. Desktops are coming out now, for example: https://softiron.com/products/overdrive-1000/
Server/HPC, there are quite a few coming online. The Cavium presenter @goingarm listed (https://www.packet.net) on their slides, might be decent for getting a cloud instance to try out. There are many others. A good place to start finding them is: http://arm-hpc.gitlab.io.
A nice thing about ARM is that you get lots of different micro-arch under a single ISA. Once the ball gets rolling there will be many processor choices to choose from, which I think is a great thing (however, in full disclosure I'm one of the authors, and I work for ARM Research for our HPC program..although all statements above are my own opinion and not those of ARM).
https://drive.google.com/file/d/0B4tfh1u3NMxnTThSdEswR2o1SXc...