It seems to me that the Chaingun nerf has been over-exaggerated. It went from 90 damage to 75 damage. This is only a 16.6% damage nerf, for a gun that had an incredibly high DPS. Even with the nerf, the weapon will likely still shred enemies. It is still the highest damage medium ballistic mount, it still fills the coveted spot of HE medium ballistic slot, and it still has the same trade-off of damage for range.
To be honest, I don't think the weapon will have any hit to usage once the new patch drops, though only time will tell on that one.