The Fremont factory is actually very space limited. Tesla might actually sell it in the future.Tesla Factory in Fremont employs 10,000 people (which is more than the Fremont Assembly or NUMMI site predecessor facilities ever employed at one time) while also having somewhat higher production figures than those two ever did.
Granted, a larger part of those 10,000 may actually be involved in non-direct assembly line jobs than the Fremont Assembly/NUMMI workforces.
If you want to see their newest tech, check out the Shanghai and Berlin factories(under construction). Their production techniques are very advanced and Musk obsession with vertical integration and automation is clearly paying off.
I am expecting their profits margins to increase even more in 1-2 years after these new factories iron out their starting production issues