% ./perl  -Mwarnings -Mstrict -e'my %a = ( a => 1); print %a->{a}'
Using a hash as a reference is deprecated at -e line 1
[download]

Well, it still works in bleadperl, which is what will become 5.10. So you're safe for a number of years yet. Rafaël announced a code freeze some time back, so a major change that would force this syntax to be retired is unlikely to happen this round.

Still, it would be a good idea to go through the code base and clean that up.