I'd say they need to introduce a new class of ship.
It would be part support ship, part combat. Each race would have different variations of them.
They would be "Sub Capital Ships"
Take a beating like capitals, yet be a lot more spammable and cost around 30 fleet supply per. Each race would have 5+ different types with different fleet capabilities to really mix things up.
More variables + more paths to victory = good game design, imo.
Heck, I'd be thrilled about just adding a bunch more "late game frigates" with the hull/shields to survive titan AoE long enough to make a difference.
A late game cruiser version of Light frigates(anti-heavy DMG & high move speed) and Flak would be greatly appreciated.
Anything to give us a late game frigate counter triangle/square rather then "mass carriers as they are the only frigate that have any survivability whatsoever late game".
Mini-capitalships could accomplish a similar result.