There are certainly areas that might change. E.g. if HP's memristor research pays off, with true random access, consider that solutions like Redis suddenly can be written to provide persistence without having to write a log to disk or write dump the data.
And e.g. consider the changes to RDBMS's if you can do guaranteed committed writes of individual bytes. A huge amount of the work on RDBMS's have been around table types that are optimised for per-block read/writes, where the design tradeoffs might be very different if you can do "cheap" random access (though caches will probably still justify some degree of block-wise access).
But with respect to operating systems, I agree that it will take a long time to see any dramatic changes. The current mechanisms would still work: Open a file that maps to a memory region instead of a drive; mmap() it. Your app would just want to know whether or not the file content is instantly persistent on write or not.
I think HP's starting point, though, is that we don't really know. Both in terms of hardware and software. Take this DIMM drive, for example. If you look at current server motherboards, a lot of servers has no need for PCIe slots other than for SSDs. A lot of them will not need drive slots at all if you can stuff that much storage on DIMM slots. Suddenly it becomes viable to put really high performance systems in half depth 1U form factors. For a lot of our larger servers, 50% or more of the server volume is air because current designs are so geared towards front loaded hot-swappable drives. Maybe 75% of the weight of the servers are due to drive bays and larger boxes to accommodate that front-loading. That's a lot of wasted metal, and a lot of wasted rack space. And a lot of wasted electronics for SATA interfaces that could sometime become obsolete.