Hopefully the latest C41 B&W film such as XP2+ has vastly superior archival properties to the earlier versions such as XP1 and the latest C41 colour neg film range is a vast improvement on say early 1970s colour neg.

I cannot comment on the longevity of XP2+. It is maybe too soon for anyone to comment until at least another 20 years have passed but I have first hand experience of early 1970s colour negs and some have begun to serious deteriorate whereas I have traditional B&W negs going back to the early 1950s which produce prints as good as the day the negs were first processed.