Maybe implement a platform that locks old posts then? I'm pretty sure reddit implements a feature similar to this.
That sounds like a reasonable solution when necrobumping isn't allowed, but I have no clue as to how the forum software works and I bet there's not an easy, automated way to do it.
I'm sure when the new forum software comes along in 100 years, all these problems will be fixed.
Why are you here and not on reddit then?
I know your question was rhetorical, but man...if Reddit was all that was available I think I'd jump headfirst off the webbertubes and never discuss anything related to bitcoin again. For all the problems bitcointalk has,
at least it's not Reddit.