So I'm in the process of trying to arrange a factory tour, and I was told there will be no tours the week of August 10th. Make of that what you will.
More likely that they will bring the second production line online. Not sure this will mean Model X production as it was meant to build both cars (from what I read here)
Speculation on my part: Logic would tell me that they keep line #1 producing model S while they start producing only Xs on line # 2. At one point (above my pay grade to say when) they start shifting model S production onto line #2. Again..speculation..There is talk of a refresh on model S. I would suggest that this refresh occurs in late Q4 or ealy Q1 2016 when the shift of model S from line #1 to line #2 occurs.