I suspect that the covered car on the far right is the Model 3 sedan. The "weirdmobile" half-n-half is simply the two variants (CUV and sedan) derived from the same Model 3 platform, siamesed for whatever reason. The exposed car on the far left is just an early Model X clay.
The car in the far right of the pic looks like a Model S, no? It's much wider than the half-sedan/half-CUV Model 3 and it definitely resembles the S...
I will say I HOPE that right-most car is a 3, because it looks low, wide, and sexy under that cover.
Increased width has advantages (safety, stability, storage) and Tesla can afford it due to added rigidity from battery. However, increased width adds weight. If battery pack will occupy floor space as it in MS width and wheel base will be a function of battery pack size at maximum capacity.
With that said, if motor's are to be interchangeable between platforms (which makes sense), motor size/mounting may dictate minimum width.