But the U.S. competition schedule has been moved around before. It really is only a matter of setting the dates and saying after the currently allotted Nationals, the new dates will be ... and do it.
The real problem is marketing. In the past Nationals was on top of, or close to other major sporting events (IIRC it used to conflict with or be close to the Super Bowl, or NFL playoffs?). They want Nationals to be at a time when there are few major (more popular) sport events scheduled. But if 4C is in mid-January, you have to be looking for dates in early December to give the athletes at least a month between major events, and now you are competing with Thanksgiving and several major sports. Plus, in December, Nationals would conflict with the Grand Prix Final which would keep major skaters out of that, so for marketing reasons, ISU would probably have to move the Grand Prix up a month to keep it a month ahead of U.S. and Canadian Nationals.
Once upon a time Nationals was even after the Olympics and Worlds.
Excellent point, it's all about finding an open slot on the calendar. In both the US and Canada, football would dominate the schedule and preclude major changes. Also hockey in Canada is a factor. Then there is Christmas to consider if you are talking about moving nationals to Dec. It virtually cuts the month in half. It's a major maketing risk to take, especially considering the fact that the approximate period for both countries' nationals is has been set for more or less three or four decades since figure skating became a real television sport.
Also, if both countries were to shift their nationals to December, then they would likely demand that the GP and other international start earlier as well. Their qualifying comps would necessarily have to move up, which means the season overall would be even longer, from say late August or early September to mid March or early April. Considering the fact that Speedy wants to add a team event after Worlds as well, the season could nearly reach May. That could be a major strain on skaters' bodies and the attention span of viewers.
It's the same issue tennis goes through with the Australian Open, Wimbledon, and the US Open. The season lasts 11 months for the top players with events every week and long, even months long, stretches overseas and away from training or rest. The French Open's placement is fine but the clay season may be a bit too long and lead to burn out. There are always calls to shift the majors' places on the calendar, especially Australia and Wimbledon. But the end of Australian summer holidays likely prevent the move to a date in Feb or Mar despite the tournament starting virtually right after Christmas. Similarly in England, Wimbledon can't be moved more than a week or two later, because citizens are starting their out of country vacations and the racing season, Tour de France and various international soccer championships all overlap. Then there is always the Olympics popping up every 4 years mid season and Davis and Fed Cup to cram in before the US Open as well. The US Open is actually a week or more too late, because the seasons actually change in New York mid tournament and the NFL season starts. But then there is more competition with golf and its final major if the even moves entirely into August.
So there are so many factors to take into account in a crowded sports field regardless of what sport you are talking about, but especially and international one. But in the end it comes down to ratings. Speedy may be facing a real uphill battle on this one. If skating RATINGS in the US were to rebound significantly, I think that would be the better time to attempt a schedule shift. Right now, there are too many tenuous factors involved.