AFAIK, as we can still use the "/" character in page titles, there never was a plan to reintroduce subpage *functionality*. But it is easy enough to to by hand: Create the subpage by clicking on a link you create on your homepage ("[[user:Magnus Manske/foobar]]"); on the "subpage", write "Back to
Automatic functionality that can be done by hand is no longer automatic functionality. And the creation of the back-link is only part of the functionality; the other part is being able to write [[/foobar]] instead of [[user:Magnus Manske/foobar]] on any user:Magnus Manske subpage.
It seems we're back at my "trusted" status idea, which was meant to *reduce* the "cabal" by making certain fucntions accessible to many people instead of two. Well, I guess I was ahead of my time again ;)
Increasing the number of people in a cabal doesn't make it less of a cabal unless the vast majority of people are in a cabal. Then you've instead got a situation of unfortunate hierarchies. I'd rather have one or two absolute dictators (so to speak) than an oligarchy.
--tc