I recall skimming some recent(-ish) IPv6 overview RFC which was an update to an older RFC, ("IPv6 architecture", or something like that, maybe?) and IPSec has b

I recall skimming some recent(-ish) IPv6 overview RFC which was an update to an older RFC, ("IPv6 architecture", or something like that, maybe?) and IPSec has been demoted from necessary to optional. So it's not entirely impossible IPSec will eventually fade into obscurity.