mmm while most road bikes probably will come standard with Disc brakes in a few years you will always have some purists or weight weenies who refuse. Honestly cyclists are some pretty finicky people and them buying your buy a couple years from now will not be due to not having Discs. If you look at any marketplace or any bike wholesaler they will tell you the most leftover are due to funky sizes and niche bikes.
I just spoke to a contact who is a wholesaler and he told me the number one overstocked bike at the end of the season is gravel/cyclo-cross. Also another common hold back is high end bikes since a lot of markets can't sell $7K+ bikes regularly. He told me a story how a client was interested in a Scott Genius 900 Tuned which is a $7K bike and how a dealer mistakenly brought one in and wasn't able to sell it. He sold it to his client for $4K while still making money off the transaction. So my point is a feature that isn't even close to being 100% adopted will not stop you from reselling your bike down the line, however resale value wise don't expect much since bikes are worse than cars