BruceHamilton:
One of the reasons for the pre-orders is the loss of the US Govt subsidy of $7,500 once total Tesla production reaches 200,000 ( all models ). Tesla is expected to be close to 150,000 before Model 3 production starts. The subsidy declines to zero over the next 100,000 vehicles. I suspect some "pre-orders" may wish to sell their position in the queue for a premium.
I'd also note that the design of the constrained boot ( aka trunk ) access due to the glass roof has engendered quite a lot of negativity.
I haven't seen details / photos, but it'll have some extra boot space in the front like the S. But yeah - I don't think sacrificing either a deep sedan boot or proper hatch because of wanting the style feature glass roof was a great move. Likewise the gullwing doors of the X - a lot of complexity IMO for a feature that on balance probably has more disadvantages than advantages.