Seed Accounts (DW's name for permanent accounts) are hopefully never going to be available again, because they were an emergency maneuver when Dreamwidth needed a lot of money very, very fast. Buying a Seed Account means that the account in question will never need to give Dreamwidth any money for its services ever again. If Dreamwidth didn't need money coming in regularly, I'm sure they'd open sales back up! Like if they got some sort of lifelong grant for the site or something, they might consider it.

Honestly, if Dreamwidth ever does need to raise a bunch of capital in a hurry, I'm hoping that, rather than selling Seed Accounts again, they'll run a sale that's like. Buy 3 months of paid time, get 1 month free! Or something. So they can continue to guarantee more money coming in when they need it.