yourbankruptcy, yes, you can do more than keeping the disk image of the OS in such a memory: You could keep the runtime image which would be instantly available on powerup!
Think of the technology industry with a non-volitile, dense memory running at the speed of DRAM: The current order of DRAM manufacturers, Flash manufacturers and hard drive manufacturers collapses. Fortunately for those companies, such a memory would be introduced over a period of years as cost, reliability and manufacture issues are resolved.