One of the nice parts of the mill deck in it's current form is the opponent tends to help you without knowing it. Shaman drops mana tide and they are working against themselves.
I'm not saying this is going to be the wave of the future top tier deck but I do see it as something fun that will come along with a few new cards. The dancing rune weapon being a staple if you are going to try and build it.
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Exactly my point on the fun factor, but honestly in CCG's what the company intends and what pans out doesn't always work out. Do you really think the first iterations of miracle rogue were thought about? It was too powerful at the time but if it wasn't OP'd I think blizzard would have broken it.
One of my favorite MtG decks of all time was the Astral Slide deck. It was something no one really saw coming and went on to win the Nationals. People get creative and I don't think Blizzard is going to break 'unintended' decks unless they are broken.