@ syntax as a synonym for user name=
In an entry, if someone types "@[string]" (more specifically, something like "(^|\s)@[legal characters in usernames]*\b), check to see if that's a username at posting time. If so, translate it internally to <user name="> syntax.
This would allow users to choose the now-common shorthand of '@username' to indicate users on the local system. This would be taking a design pattern that has become mainstream over the last several years, which users are used due from Tumblr, Slack, Twitter, etc. I'm not suggesting auto complete; there are too many more important pending changes to the post system. I'm also not suggesting a variant for the other-sites functionality of the user element; no @username@twitter, or something. Just a very straightforward replacement. But this would be a nice shorthand that users have become accustomed to.
Should be implemented as-is.
Should be implemented with changes. (please comment)
Shouldn't be implemented.
(I have no opinion)
(Other: please comment)