I wouldn't be so sure. I suspect Directv has better lawyers than Weather Nation and they may have included an "out" for Directv, if they chose to use it. I can't just remember how E* ****ed that other, smaller weather channel (can't even remember their name now - nor does it really matter).
I am pretty sure Weathernation will stay. Who knows we might get Accuweather too, and you might see a better weather mix channel coming!...