Recently, reports of Twitter's intentions to delete inactive accounts, starting December 2019, came to light. However, the company has come up against resistance to this idea from more vocal users. Their main objection appears to be that the move would result in the removal of the timelines of the dead.
https://www.notebookcheck.net/Twitter-walks-back-its-plan-to-cull-inactive-accounts.444953.0.html