According to Google, links form de-indexed websites simply loses their value. They don't hurt negatively if they are left alone.
Google after the last recent updates, started to take into consideration many negative SEO related measures. If they penalize websites that gets links from de-indexed websites then we can spend the whole day penalizing our competitors and ranking on top of them.
In few words, focus on your content, build quality relevant links, connect on social media networks and you must be good to go!
Hope that helps!