My take is that you can't look at 260 vs 1500 as a some kind of ratio to predict how many Model 3s they're going to build. Tesla learned a lot of lessons with the S and X, and designed the Model 3 to be more easily manufactured. The S pretty much had to be the best sedan ever made in order to overcome the negative mythologies of EVs at the time, so any issues with regards to ease of manufacture were secondary. Tesla probably would've failed if the S wasn't the best ever.
The critical battery manufacturing plant is up and running on time. The production lines are ready to go. So it sounds like the Model 3 manufacturing machine is 99% ready to go, but their timeline was very aggressive, so they're working out some bugs and supplier issues. The whole production system can only get running once those issues are sorted out, so initial production isn't really a rate of cars per week, because it's going start & stop right now. I would think they have to stop the production every time they have a bug or a flaw, but once those things are fixed, the whole thing can get going to full speed pretty quickly. As soon as those 1 or 2 suppliers with issues are sorted out, and the initial bugs are fixed, the product will ramp up very quickly.
so I expect them to product more than 200,000 Model 3s in 2018. Possibly 300,000.
It looks like they're shipping a product with a minimal feature set at first, since most of the features can be added via wireless updates, which is smart. It lets them get more cars out the door faster, and people with early cars will feel like their cars are constantly getting better.