Can we allow some level of site specification for this? I can see that being able to specify any SE site would be problematically annoying. But I think that at least being able to specify, for example, tags from the parent site when posting on the Meta site would be useful. On the Meta site for any Stack Exchange site, proper tagging is a very common topic of discussion, and being able to use the new tag formatting will roll right in comfortably. But currently, instead of linking to the tag you actually mean, it'll link to the (typically non-existent) Meta tag.
This does not apply retroactively, but any post containing the old
This is going to sound a bit odd.
An easy fix to make these tags more usable is to only link to the parent site, or in the context of this question, point there by default. This is really just a metadiscussion shortcut (instead of doing the
In fact, I don't really see the point of even having them enabled on the parent site at all. If a question is a discussion about tags on the site, it's a meta question and should be migrated. (And anyone doing that likely won't be savvy enough to use the new syntax anyway.)
In summary, I think the default target for the tags should be the parent site. Changing the site target would be a nice ability to have, but we could probably do without it if the tags only ever linked to the parent site.