Re: Alternative to Optical Storage????

NONE, really.
If you need long-term, optical is kinda IT.
I'd suggest "M-Disk".
Mag disks can be FAIR - but CAN suffer from
"bit rot" after awhile. There are utilities,
or you can write one, to read and re-write
every so often. Not esp hard to script
something like 'dd' for the purpose. Wrote
a handy friendly util in Lazarus Pascal, but
needed a 'C' helper to deal with large-TB
drives as FPC only *thinks* it has 64-bit
disk functions.
Flash and variants - CRAP.
Magic crystal holograms - CRAP.
Tape, CRAP.
FRAM, good, but very low capacity.
Oh, and VERY important - will there be DEVICES/DRIVERS
to READ your preferred medium even 5 years from now ???
I've got these 8-inch floppies ......
IMHO, your best bet is REPLICATION. Keep moving yer
data to the currently-popular media. Using 'cloud'
can help too - but don't compress/encrypt with
utilities that may not stand the test of time.
Plain-Jane ZIP will last, others ???