“Necessary” is a big word, madam. If we look at the history of NORAD, we've evolved. Today's NORAD is not the NORAD that started in 1958. We've evolved to address the threat to Canada and the U.S. in a combined fashion.
In 2005 General Eberhart, the former commander of NORAD, was asked after 9/11 what kept him up at night, what threat he thought we needed to pay more attention to. He said he was concerned with the maritime approaches, and stated that he needed a maritime NORAD. Well, he didn't need an additional NORAD or a maritime NORAD; the right thing happened, and NORAD evolved into the maritime domain.
If we look at cyber, if one day either party to the agreement, Canada or the U.S., says we need a cyber NORAD, I think it would be wise to have NORAD evolve into the cyber domain, instead of creating a separate agency, and deal with cyber in a binational fashion.