Not anytime soon...though I have no idea of a timeline.
Why would they do it?
IMO, the point of 9/11 was to suck America into direct involvement in the Middle East...and it worked (sadly) beautifully.
Now all ISIS had to do to get America riled up (to a much lesser extent, of course) is behead a journalist on video and post it on twitter. This should keep the American masses okay with direct involvement for a while. And when they tire of it - they have another hostage to behead.
Why run a huge terrorist attack on America to get America to commit when killing individual people in horrific ways is so much cheaper/easier?
Unfortunately, the masses are easy to bait.