It is a partial deal breaker for me because USB-C audio doesn't have a standard. I have a cheap USB-C headphones I've tested with my 950XL, Mi Note 2 and the V20. With the WP and more importantly the Mi Note 2, it was plug and play. With the V20, you had to manually select the audio option - not convenient.
I don't mind killing the jack, but USB-C audio isn't ready for primetime without a set standard and headphone options being sparse. Not everyone wants to use BT headphones and they do die. To me, it doesn't make sense without a situation where you lack a standard profile. OEMs should be allowed to have custom headphones working with their phones (in a profile) but you shouldn't be tied to a dongle that's hard to buy if you lose it.