I don't know why I keep watching women's distance races, when I know what the outcome will be. The only way Johaug could lose is if there is a change of weather during the race and the seeded athletes get the short end of the stick, like Falun 2015. Or she races sick or injured and just doesn't have it. The 2016 ski tour Canada, at the end of the season, Weng was able to stay with Johaug and beat her twice. Last year in Quebec at the end of the season, Nilsson stayed with Johaug and beat her, twice. The course in Quebec is nowhere near as tough as Canmore, and a bigger, stronger athlete like Nilsson was able to stick in there and use her power to outsprint Johaug.
The Davos course is all climbing for the first half and all descending for the second half. That's why the huge gaps developing already in the first few k's and why Johaug's lead didn't balloon to a minute or more.
From 2007 when Johaug broke through to win a medal in Sapporo at the age of 18, to 2011 (in 2011 she broke away to win the 30km in Oslo), there was more competition in the women's field. You had the Finnish duo of Kuitunen and Saarinen plus strong teammates like Roponen. Petra Majdic was there for Slovenia, always in the running for podiums, especially in classic events. Ariana Follis and Marianna Longa, Magda Genuin and Sabina Valbusa for Italy, Evi Sachenbacher, Claudia Kunzel, Kathrin Zeller, Stefanie Boehler, Nicole Fessel for Germany, young teammates of Johaug like Jacobsen (still going strong!), Kristoffersen, of course Bjoergen and Kowalczyk, Kristin Steira who was always a contender in distance races, Shevchenko for Ukraine, Skofterud (RIP), a young Charlotte Kalla, Korosteleva, Khazova, Medvedeva, etc. Now we're happy if Johaug doesn't win by more than 30 seconds, which she won by today.
The women's field is lacking and it has gradually gone down in quality over the years. The Swedish women, the Russian and American women, and Parmakoski have had made it to the podium in the last couple seasons to join Johaug, but beyond that there's literally nothing, and beating Johaug in anything 5km or more is rare.