Just to be clear, I'm arguing that there _does_ appear to be evolutionary pressure here, so we probably will evolve in response. That argument doesn't require predicting how exactly we will evolve; you're kindof asking an orthogonal question. But I don't mind orthogonal questions, and I can imagine some ways that we might evolve in response:
1. Human reward-seeking becomes longer-term, with less of an emphasis on short term rewards. I'd bet this trend has probably already been ongoing for a long time. But I wonder if there are some negative effects of this -- for example perhaps it takes us longer to learn things that truly do have very quick, direct feedback loops. Maybe it takes us longer to learn how to walk, swim, etc as a result.
2. Screen-avoidant communities start to dominate the human population. Eg, Amish communities, "traditionalist" communities like that, your friends that religiously don't use social media, etc. I'd bet this is already happening too! Would be really interesting to look at the proportion of new births, perhaps controlling for usage of birth control. I wonder if this effect could result in humanity generally becoming more religious (as opposed to the recent trend of becoming less religious). Admittedly, this is more of a cultural change than a change in our dna, but I feel it fits the category -- it's a widespread change across humanity in response to the pressure of distracting apps.
3. Humans grow a stronger distaste for blue light. I suspect this wouldn't be the "end" state, because if it happens we'll probably just start buliding devices that put off less blue light.