This seems like a preemptive, rhetorical question, not a "now that I have done this, what happens" question.
The answer to the question for the OP is that any discounts apply to the specific vehicle. If the vehicle is rejected, you will generally go back in line. IF there happens to be another acceptable car that is not assigned to someone else on the lot, its possible that your order could be swapped to that, but whatever price that vehicle is, is what it is.
The expectation should not be for Tesla to automatically transfer any discounts to any potential other vehicle. I even remember a thread here where Tesla itself wrecked the car that was supposed to be delivered to the person who started the thread, and still did not want to transfer any discounts.
So, TL ; DR
1. If OP cancels they should expect to get back in line (and possibly not take delivery by the end of the year)
2. They should expect the $250 order fee to be able to be transferred to another vehicle, if this is the first time they have canceled
3. They should expect any other vehicle that they might pick to have its own price, which has nothing to do with the price of the canceled vehicle. It should not be expected for Tesla to let them buy a different vehicle at the agreed upon price of the one being canceled.