Tesla still hasn't fully developed a lot of international markets. This year they will be opening in Mexico and Korea so that should help with orders. Korea is a huge market for Tesla and should be one of the largest markets for Tesla(Mercedes sells more S-Classes in Korea than they do in Germany). Mercedes sold 10,000 S-Classes in Korea last year, Tesla could probably reach a similar number with the Model S once they enter that market(big EV incentives 15k per vehicle).
Also, Tesla still has a lot of room to increase demand in the states. Half of their orders come from a single state (California).
If they were demand limited they would probably open more stores in different markets. There are still markets in Europe they haven't opened up in yet (Spain, Southern Italy, and Russia). Furthermore, there are still major markets in the Middle East and Asia that Tesla can expand into.
In the Q&A from France:
QA With Elon Musk in Paris - YouTube
Musk mentions that they are currently producing 1,000 Model S Sedans per week and sometime in the second quarter they will reach a similar level of production with the Model X.
In the Model X thread:
- Page 13
They mentioned that the factory is only producing cars 4 days a week now with 12 hour shifts --> so 48 hours in total, up from the 5 days, 8 hour, 40 hour weekly shifts.