Are you an attorney?
It may say 2020, but if the dealer reached out with an order form this week, they are honoring their 2020 proposal and soliciting THAT sale.
"Your honor, we came to a written agreement with the defendant for a car that turned out to not exist. With the current model year however, we believe something similar enough has been produced, so we offered it as a consolation at the price being offered by us and other nearby dealerships. The defendant turned down that offer. Their deposit is listed as non-refundable in the written agreement, so we consider this matter closed."
The only objective parts of this case would be the written agreement for a car that doesn't exist and the downpayment. Everything else is just subjectivity and spoken words.
All that said, since it's a written agreement for something that doesn't exist, maybe it could be nullified in whole and OP could get their deposit back.
I dunno. The whole situation is weird. A dealership making a written agreement and taking money for something absolutely speculative without even a teaser from the factory? The whole thing is just asking for a situation like this.