Well they haven't had to face Weaver/Poje yet, who are a stronger team than those they faced at GPF and Nationals. Hubbell/Donohue's RD imo, is a shadow of W/P's 2014 FD with the same music. Many people underestimated Weaver/Poje for Nationals because they didn't compete on the GP, even though they had been alternating performing their RD and FD on the TTYCT. They pretty much got all their KP's and some level 4 step sequences at Nats. I'd say they have a very good shot at their third 4CC title, after they claimed their third Nationals title.
The problem is W/P haven't competed since September, and their one competition was Autumn Classic, on home ice, where they faced Smart / Diaz and Wang / Liu, hardly top tier competitors. Doing their programs on the tour is no substitute for competing against their top rivals because exhibitions aren't judged. OTOH, H/B have been facing top competition all season and the ISU judges have given them high scores.
Of course W/P won Nationals---they were 2018 World medalists, and G/P have had a disappointing season. No surprise there, and of course Nationals judges and tech teams tend to view their star performers with rose-colored glasses, hence the P/C level scores. But it's ISU judges and techs at 4CC and Worlds. While both Canada and the US will have ice dance judges at 4CC, neither country will be on the Worlds ice dance judging panel. Canada will have a judge for Men and Pairs, and the US only for Ladies.
Given the judges chosen for ice dance (AUS BUL CHN FRA GER HUN ISR JPN POL KOR RUS TUR UKR) there well may be a Russian dance team on the Worlds podium.