Of course there will be people who stop flying DL because of this. Just like there were people who quit DL when they added MQD requirements, and when they switched to revenue based mileage earn the following year. I'm sure that DL would rather have people stay, but they are certainly aware there will always be people who leave because of such policy changes. Others will stay and just live without lounge access (and there's a 3rd category who will spend more on CC's/fares to keep getting access). It's not actually a binary choice. It's just business, not personal. FTers seem to generally obsess about these things more than regular folks who can just move on.