Im most excited about the potential for crystal based storage. Right now there is work being done to etch silica glass internally, allowing for incredibly long term preservation and durability. It can even be rewritten, though the tech is definetly best for achival purposes and is being pursued primarily by movie companies wanting high quality storage.
DNA also sounds interesting, though it doesnt seem like a good way of preserving data long term. DNA is very fragile, and seems like an odd route to take for long term archiving.