Yes it's called bank switching
You call also connect up a disk on chip or any of the other myriad of things.
None of which is very exciting unless you have a particular use for the banks.
It's something from what I understand that will never appear of the PI in their design because they already have track routing issues under the SOC. The whole project almost didn't get off the ground because of that problem.
From what has been stated from the foundation in terms of even getting a true USB3 hub you probably have zero probability of getting a memory bank option for what would be a few edge case applications that could ever use it.
As with what they said with the USB3 case you might as well ask them to design a whole new SOC if you go that far.
I would take an RTC first over anything else so at least you can keep time and date when you don't have the unit connected to the internet. In baremetal it's annoying having most of your file write times with some stupid and totally whacky date time because you have no idea what the date and time are unless you buy or design one to plug onto the IO bus.