> 
> 
> How would it be different from the target attribute as it now works?

"target" has never been in the strict version of any HTML standard.
It's de facto deprecated, presumably because it is behavioural and
has similar problems to frames in terms of creating a world wide web.

(The argument I've heard in the past for why it and frames are not
formally deprecated is that you cannot deprecate something that
has never been in the standard!)