Yeah i know they can be used in wild mode which is why i wonder if your gona play for rank why collect cards when they will just be retired the next season afaik. Yes it keeps things new and interesting but soon as you have a good deck and worked ur nuts off to make it with new cards and then retirement phase comes in, your gona be like wtf. So i dont see the point. I know mtg done it and it worked well for them but as far as i can see they play very differently. mtg is more complex, hearthstone is rather more simplistic in its cards and gameplay.
And wild i dunno can you earn rank and get rewards like the new mode will be or not. If you can, how long till they start nerfing wild to force you to play the new mode instead?