I haven't found much info comparing the longevity of archival Blu-Rays to DVDs.
Lots of speculations from 4 years ago, but not much from the recent years.
Any decisive info on whether they will last at least as long as top quality DVD+Rs?
You do know they have MO disc in DVD and BD for long term storage. Degradation of media playback beyond the media substance and chemical used will also depend on how you protect and store the media from heat source that will shorten the lifespan of the media to hold the data.
Are the new M discs even better than the MO discs?