My first reaction: "no, why, I loved the DW, they can't close it". Then I realized I haven't used it in a month or so. And consider I'll have XY at that time, I doubt I'll really miss. I hope the new DW or whatever they decide to do will be nice.
Though like AdrianD said, I'll have to play it more often now to get more DW Pokemon, hehe.
You won't be able to change your C-Gear and Pokedex skins after it closes, so be careful which ones you chose to use in your game.