I forgot to clarify and I should have, that I was mainly talking about the packaging of the platform. As in rear motor, RWD, balanced placement of batteries, independent rear suspension, similar designs of powertrain/motor, wrapped in a 5 door sedan/hatchback.
If you sit in a base 3 series, that are appx $35k, their interiors aren't in any way 'premium'. Minimalist, good enough, but not $70k 5 series level nice. Yet I consider the philosophy of the 3 series as a shrunken down 5, which in many ways it is. I don't expect much use of aluminum either, but the Model 3 having a smaller footprint compared to an S, will in my estimation mean that the weight penalty of conventional steel will be offset by the size.
The materials can be mid level Honda Accord nice, and that IMO will be good enough. Do I expect a 17 inch screen, not quite but a 12-13" is feasible and not out of the ordinary. I do disagree with your statement about the Model 3 not being updated with OTA software, with AP, etc. This is in Tesla's DNA and I'm willing to bet that the Model 3 will definitely have OTA updates as well as the $2500 AP option as is afforded to the S and X
Now compare this design to a Bolt, which is in its packaging and platform, a sub compact econo hatchback with a torsion beam rear suspension and front wheel drive. The driving dynamics of such a design (barring something like a Type R Honda) leave much to be desired and in no way compare to something that was designed as an optimal, nearly no compromise, and without being constrained to be loosely based on a legacy conventional ICE platform. The Model 3 should and most likely will be designed as a sporty sedan EV first and will bring with it all the advantages of a clean sheet design with no constraints.