We don’t know how the fediverse would play out in the long term but I expect a few things:

• Lemmy devs will implement locking old posts in the future
• instance owners will decide on their post locking policies
• Many instances will not survive for as long as Reddit survived till today
• Third party archivers (perhaps archive.org among others) will need to step in and archive posts. Ofc archived posts is not interactible.

The millennials are in the absolute worst position tech literacy wise. They had the boomers on one end and the zoomers on the other.