I had a look at the canadian website and only 1 or 2 shades were sold out.
Then, I asked to a MA if they were going to were going to be permanent and she said that she was doubtful since they just came out and Corparate could take a decision so fast. Her store actually didn't sell them that well compared to others.
She also thinks that it is weird to make them permanent just if they sell out well in the US when they didn't sell out in Canada, where MAC is from.
Unless it would be an exclusive product but I doubt it for a whole line.
I guess that we will hear more later.
My feeling is that they are relaunching some more colors in a next collection (but propbably not a permanent one yet at this stage) and maybe this is what people are getting confused with.
I heard that the MAC updates for the next collections start next week so we should know more very soon!