A quick glance at Coarray Fortran [0] shows that Coarray library is built on top of MPI instead of replacing it.
MPI and InfiniBand are irreplaceable technologies for HPC clusters as of today, both in terms of speed and latency. Lastly IB is not a connectivity layer. It's a HBA which carries information from memory space of one application to another. So it's properly "Magick" in terms of programming and research.