There is a pcgames.de interview that can be found at:

http://diablo.incgamers.com/blog/comments/jay-wilson-interview-pcgames.de/

saying that there will be 5 artisans. Exact quote: "The first three Artisans (there are going to be 5 different Artisans, though only 3 have been revealed so far)"

Did something get lost in translation here? Cause I haven't heard this anywhere else.

Edit: Warning the above linked interview contains spoilers.

There are three artisans total. It's likely that the confusion came from each artisan having five upgrade 'levels'.

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Q u o t e:
Blizzard does spoil quite a lot.

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lol?

Yes that was the final stage of the blacksmith, although pretty much final nothing in the video had final lighting or effects so it'll all look even more awesomer.