How are snub fighters supposed to remain relevant? What's the role of snub fighters in the universe?

That's a very existential question. Snub fighters are...

Snub craft. Not all of them are fighters.

They're parasite ships, in terms of they require a sort of mothership to transport them around. They don't have quantum drives. If you have a quantum drive, you're not really a snub ship. We give them a different name. It might be a scout craft or something like that. So they require another ship to cart them around, and they're really there to provide protection. For things like the Corsair, it's a Constellation competitor. The Constellation has a snub craft and two turrets. The Corsair has three turrets and no snub craft, so they provide that alternate defense. Offensively, they're never going to win a huge fight. They're there to provide protection from things or provide deterrence.