Given the fact that we already possess point defense systems (both ballistic and laser) that can vaporise incoming missiles I'd wager space warfare would return to ballistic weaponry of some kind. The distances involved in most combat would make it difficult to sneak any sort of self propelled device past enemy defenses. Maybe even some metal storm kind of device that launches dormant projectiles that self activate guidance systems after a programmable time.
Imagine if that weapon fired ballistic shells. Those shells activate at a pre-set distance from the enemy ships (regulated by a timer or transmitted signal). Using very small thrusters they orient themselves to launch an explosive payload on an adjusted ballistic trajectory. These rounds are difficult to detect because for most of their lives they travel inactive, and randomly changing course upon detecting launch doesn't guarantee safety because the explosive payload is deployed on a corrected trajectory at a much closer range, giving you far less response time. That combined with the number of shells may overwhelm any point defense system. I know it's like a gun shooting another gun that shoots a bullet at the target, but it seems like an example of the creative means you may have to take in space warfare. Drones could be used in a similar way. Launch them as a projectile and activate at attack range.