I like [Tim's] proposal because it is both useful and technically sound - a rare combination these days ;)
It's not clear to me from Tim's description exactly what he's proposing, so let me paraphrase what I think he means:
1) No meta tags (#base, #context, #parent, #alias, or all the variants we've discussed over the months), no new name spaces or runtime-features of any kind.
2) As purely a typing convenience like ~~~, links typed as [[/baz]] on page "Foo (Bar)" are rewritten when saved as [[Baz (Bar)|baz]]; links in the form [[/baz]] on page "Foo" are rewritten as [[Baz (Foo)|baz]]. If the link already specifies a display form (the part after the vertical bar), that display form is used as is.
3) Links with non-initial slashes are not modified at all. 0