Twitter will remove inactive users from 11 December. Consequently, some older usernames are going to be released eventually.
Twitter points out that it will gradually eliminate inactive accounts. As a result, their tweets also go away, plus they no longer add up as fans with some other profiles.
For balances of deceased individuals, the organization is thinking about a sort of Memoriam where the tweets of that individual can be preserved, but just how exactly that will work will not be yet clear.
As accounts are cleaned up, the consumer titles of these profiles will also be introduced. When that happens effectively is not known. The Verge information that most mixtures with five letters have already been consumed nowadays, some of them could be launched in the long term.