"anymore"

Except that the sentence you propose has a meaning opposite of the the original sentence... You would have to say "They are not that common anymore."

If you substitute "these days" or "nowadays" for the "anymore" in this type of construction you'll get the same meaning, Caspian. Guess it's a colloquialism, but from the responses here it's pretty hard to pin down exactly from where....

Sorry about that, it was a bad typo..lol.. yeah its They..