I understand that you’re probably asking Funcom and not looking for players’ opinions (and debates), so I’ll try to keep this as short and informative as possible.
Funcom has clarified that foundation stacking is an exploit [in August last year:
Given that it’s considered an exploit, and given that it’s a bannable offense right now regardless of when the base was originally built, I’m reasonably sure that Funcom won’t change their attitude towards it after 2.8 goes live.
Think about it this way: they implemented the anti-undermeshing mechanism, but they’ll still ban you if you manage to build an undermesh base.