I doubt there will be much, if any, hard plastics in the Model 3. Soft-touch materials are not that expensive and are in cars far less expensive than the 3. Base seats are already fabric in the S, so its a given that would be the case for the 3. Shittier sound system is doubtful, since the base one in the S isn't something Tesla spends a ton of money on in the first place. It's 40% software they already developed, 40% speakers which are actually dirt cheap when they don't have a retail mark-up on them, and 20% PC hardware that would be in the car regardless. Leather quality a step down makes no sense, since the Leather is an option in the first place. Less soundproofing.. ok, maybe. Retracting handles, that's a given.

Model 3 will absolutely be a $35k car. The base car isn't missing any killer features that are must-haves for the market segment. Arguing about that's not the true cost of the car because 70% of the people will order option X is silly, since that's not unique to Tesla by any stretch. Nobody is arguing about how a BMW M3 isn't a $35k car, so why bother with pointing this out?