I've had several questions about usernames here on the new forums, and what happens to folks who were registered on the old forum but have since discharged or retired etc.
As we did last forum move (Jan 2016), any currently active member will be guaranteed their username on this new website. I know there's some difficulties due to MILPAC profiles not being up, but we will get there. This policy also extends to Reservists, due to them being still regular members for the intent of this issue. Finally, Wall of Honor & Arilington usernames are also 'reserved'.
As for Retired or Discharged members - their names are 'in the pool' so to speak. Unless they register here and get a 'basic' MILPAC setup via request, similar to the previous forum, their name is un-reserved and can be taken at any time by a new recruit.
The new ticket system that is soon to be online will have a category for S1 tickets for RET/DISCH members to 'gain' their Milpac back. I will guarantee any tickets being held up due to MILPACs not being ready.
There are some teething pains with the new version of milpacs, and as such S1 can't process your accounts to give you the right forum permissions until that's done. I'm waiting on some bug fixes from the developer, but that may not come until after the weekend.