Well, recordable Blu-ray discs use an inorganic dye, so they should last longer than DVD-Rs and CD-Rs. The manufacturers typically claim a lifespan of 100+ years.
Beware BD-R LTH media, which use pretty much the same type of organic dyes as are normally used for CD-R and DVD-R as a cost-cutting measure. BD-R HTL uses phase change in an inorganic alloy to record bits, which will almost certainly outlast BD-R LTH media (and probably DVD-R and CD-R, too).
I've been using these for archival recently. (I'm almost out, too...was going to put in an order, but (1) they're currently out of stock and (2) their per-disc price may have gone up substantially since my last purchase.