With the death of New England Nordic skiing apparently at hand, we need to find some other way to move across the varied surfaces we now find in the season we called winter.
The best answer is a giant gerbil ball with studs on the outside of it. You know those little plastic hollow balls people can put their pet rodents in so they can roam freely around the house? Imagine one big enough for a human.
The ball will protect you from whatever form of precipitation the spiteful season throws at you. The studs will provide grip in snow, ice, mud or frozen ground. The ball will float, so you can navigate across small streams and rivers.
Within the ball you can run, walk or crawl. With proper padding you can even let it roll down slopes while you just bounce around. That may not be the best idea, but it's no worse than a lot of things people do already.
Nordic areas already mark their terrain to indicate the difficulty of it. Those markings will apply equally well to Terrain Balls. All the usual warnings about liability will also transfer to anyone who wants to try rolling across the landscape. Very little needs to be done except to equip your Nordic area with a rental fleet.
Come on. There's money to be made, if you just have the balls.