It appears, both by my experience with 90 years of various family photos and negatives on all kinds of bases in all kinds of storage conditions, it's impossible to predict what will or won't happen. I mentioned the many slides, both chromes and never-intended-to-last-long movie print stock looking just fine after forty years in PVC.
I have several hours worth of 16mm film, acetate base, 1928-1948, all in perfect condition. After being stored in a garage in FL for 55 years! Two rolls of 8mm, no idea of age, one looks good, the other is totally destroyed.
Many hundreds of B&W negatives from my father are mostly just fine, ca. 1952-1959. Most were stored in kraft paper sleeves of the day. Who ever heard of archival? However, a few dozen degraded either partially or totally. In my research online, it appears that there have been a number of integrity failures by Kodak over the years with the same film base type. Some, like some movie filmstocks, started acetate degradation in a matter of years, that was back around 1950, IIRC. And then they got it right again.
My oldest Kodachromes are ca. 1938, 35mm. And a number of 4x5 KC's, all in perfect condition.
Per a previous comment, yes, PVC outgases, but do we really know if those gases affect the dyes of substrate integrity? My experiences say they don't, others have reported cataclysm. I will conject that old fashioned glassine is the way to go. Back to the future.