A Sony spokesperson just confirmed that the company won't be attending E3 2020, because it thinks that the event is not an ideal platform to unveil the PlayStation 5. This makes it two years in a row, as Sony was absent from E3 2019 as well. The company is likely to reveal the PlayStation 5 at one of its in-house events.
https://www.notebookcheck.net/PlayStation-skipping-E3-for-the-second-consecutive-year.450170.0.html