Just because it looks - or IS - new when you put it on the shelf doesn't mean it will work when you need it. Time does all kinds of bad things to machines, just like it does to us. Plastics get brittle, rubber crumbles, lubricant dries out and turns to adhesive.

Sorry for the gloom and doom, but it's true!

I think it's also true that optical media is risky for long term storage and the higher the density and recording bit rate, the weaker the write signal becomes, implying the need for easier phase change in the medium, implying less resistance to reversion to the unrecorded phase state with time and temperature.

Of all rewriteable digital media known to man, tape probably has the best actual track record as a long term storage medium. Engraved stone tablets might beat it, but I don't recall seeing any stone tablet writers at Amazon lately.

And of course different kinds of tape have different long term archival characteristics. In today's world, LTO is about as good as it gets and there are millions of drives out there, so you should be able to find something to read back your tapes for the next 10 or 20 years.

And by the way, a key question when talking about "long term" should always be "how long".