Pull the power cord, pop the modules, om nom nom tasty non-volatile data. I'd expect encryption paired with MRAM if it replaces DRAM in my general machines
That's already possible with dram - just cool the modules and pop them out quickish.
The difference is that, unless you spray the coolant within 10 seconds (DDR 3) after poweroff, all data in the DRAM is lost. On the other hand, a MRAM laptop without battery will retain all the data even if the power loss occurred days ago.