There's a lot of pressure on Killzone: Shadow Fall to deliver when it launches with PS4 next month. At least the campaign should have a good amount of content, as game director Steven ter Heide has stated that the campaign should last over 10 hours "for most gamers."
This is alongside the game's multiplayer, which launches with 22 weapons available. The idea is for all weapons to be available from the get go, with attachments and customisation options unlocked through playing and completing certain challenges. Guerrilla has confirmed that the multiplayer will have dedicated servers.
Unfortunately there's no plans for split-screen support. Online co-op and a hoard mode will become available at some point post-launch.
So, there should be plenty to keep you going.