I went through this little exercise after the reveal due to learning when the AWD might be available. I didn't order on Day 1, but day 3 (had to convince the wife), and I specifically want AWD, which per My Tesla is not until Oct-Dec 2018.
My thought process went like this. I suspect that the full federal tax rebate will be used up by then (it might still be in the $3750 range, or at least the $1875 amount.) Taking that into account, and the fact that Colorado has an additional 5k currently, going the Model S route has a $12.5k incentive right now vs. a "who knows what will be available in Oct - Dec 2018" amount. (Maybe $0, maybe $1875, or $3750, or $6875, or even $8750.) Since that is too far in the future to know, I will assume $0, and anything available is just gravy.
Of course, even with the current $12.5k incentive, the S AWD is still quite a bit more ($80.5k with EAP and blue paint). than what I could get in Feb-Mar 18 if I settled for an RWD, which I won't, so it doesn't really factor in. (Even though I am suspect the same $12.5k incentive would be available then.) However, I never planned a RWD model 3, or on the bigger battery, as I was/am happy with 215-220 range, so spending $9k on something I didn't want/need would just eat into that incentive on a vehicle I didn't want. So, still focusing on the AWD model 3.
So finally, assuming the base $35k model 3, AWD costing 5k (like the S, even though I believe Elon indicated it would be cheaper per a tweet), 5k for premium, $1.5k for wheels, and $1k for paint, that comes to $47.5k, which is $33k less than the AWD Model S before incentives. With incentives, it is still $20.5k more for the S, and that assumes there are NO Federal or State incentives when I am ready to buy. That is a LOT of money.
What would be interesting is if Tesla brought back a 60D (or whatever they called it since they seem to be moving away from battery size labeling) in the Low / Mid 60's, as a way to reduce some of the Model 3 pre-orders. That would maybe make the difference of approx. $10k, which is still a lot of money, but more palatable when you consider the differences between the S and 3.
Sorry, that was long....