Odds are that'll be fixed. Current thinking is that the contents of variables that are interpolated in will be treated as just plain strings, and not regex metacharacters.
It's not out yet, but it'll be in A5 if Larry decides to go that way. There'll be a switch or set of metacharacters to enable treating interpolated scalars as part of the regex. if he does.
The ability's not getting taken away, just the default treatment may be switched. (Which is what people need and expect more often than not anyway)