I'm not sure where your information about the 15 elite nights going away in 2019 for the old version of the card came from.
They've made it abundantly clear that there's a 15 elite night cap per Rewards member per year --- no matter how many credit cards you might have --- but that's about it.
My "classic" card renews on January 6, 2019. I'm expecting the 15 elite nights credit to post.