Keep going machu, you'll get your shiny Houndour!
As for me, I've already MM a shiny (actually 2) of my favorite poke, Rhyperior, in SoulSilver waiting for me when PokeBank is out. I've also always wanted a shiny Metagross as well after seeing it debut in the anime some time ago, and so I managed to MM a shiny Beldum in X and Y!
I'm currently working on getting a shiny Hawlucha with MM. I wasn't a fan of its normal color palette, but I've really taken a liking to its shiny one. The contrast of blue, black, and red remind me of gum/candy for some reason lol.
For those that really want their shiny pokes, I'd say the time is now to go for it. X and Y has pretty much reduced the odds even further than last gen, though the exact number is still rumored, from personal experience and reading of many others experiences I believe it to be true. Also with X and Y introducing new methods, along with the old ones, there's plenty of ways to hunt for a shiny poke. Here are the methods that I can recall: Friend Safari, Horde Encounters, Random Encounters, PokeRadar, Masuda Method, and Chain Fishing. Best of luck to all who join the hunt!