I didn't get a chance to see what long-term progression systems were available.

It looks like they were going with the Helldivers 2 Warbonds mini-battlepass system which has some mechanical unlocks (a silencer in the Server Slam) and some cosmetics. If they can keep adding new items and mechanics at a good pace then it can go a long way towards keeping the gameplay fresh.

Either way, I bought it so I'll be playing on launch. :D