In winter sports there is no growing of the sport. On the contrary even, fewer nations are relevant there year after year. Finland has completely fallen off the cliff, first in ski jumping then in cross country. Germany in alpine skiing and not looking all that great in biathlon either. Canada is gone in alpine skiing too. Czech Republic is gone from ski jumping and we're like one Olympic cycle away from Poland being gone too. The ski jumping struggles to even field 50 jumpers at World Cup level these days if the event is held outside of Europe in Russia for instance.
Even if the reason is the growth of freestyle skiing it doesn't explain how former powerhouses are completely irrevelant in certain events. It's been 20 years since the Lahti WC doping fiasco derailed Finnish cross country. That's like two full generations and their answer is a 42 year old RL Roponen?
Putting on mixed relays solves nothing. Cross country goes down with inbreeding and will become more irrelevant year by year. Only Norway, Sweden and Russia seem to care about this sport these days and everyone seems to be fine with it. FIS can sell these new ideas but nobody is buying that.