I'm sure there is nothing wrong with the 25 wssm but as an earlier poster said I can't really see why anyone would prefer it over the 25-06. The ballistics for it aren't any better and you can get 25-06 ammo virtually anywhere. Cheaper too!
And as for the ammo becoming less available in the coming years, yes it will. Hell, it's not that available now. Most of the stores that do have it only have one type. So much for trying several brands to see which your rifle likes.

Yeah, I know the 25 wssm can be had in a short action. Well, quite frankly I think that's highly overated. I've never gotten half way to one of my shooting houses and thought, "Dang, I sure wish this rifle weighed 6 ounces less."

"Did you go hunting today Todd?" .... "Nope, got half way to my stand and had to turn back."....."Did you get sick?"......"Nope"......"Forget something?"......"Nope, rifle weighed 6 ounces too much. Couldn't make it there."