Going through everything logically, I think it’s like this:
T3 Frigates: Makes no sense, we already have assault frigates, this would cause too much overlap.
To expand my thoughts a little: Making T3 Frigates like the tactical destroyers would cause massive overlap with assault frigates, the poor things really don’t need this. And making T3 Frigates like strategical cruisers would make a confusing mess, since now we would have T3 Destroyers functioning differently then both larger and smaller ships.
T3 Battlecruisers: This could work. We still have some hulls free that are only used for T1-bcs, after all.
T3 Battleships: Again, we still have some hulls free to be used for this. I’m just not sure if the resulting power-creep would be good for the game.
Also, the battleships should have no covert-ops subsystem, as that would make them better than Black Ops battleships, which is ludicrous. A Black Ops subsystem, maybe?
T3 shuttles: Completely useless. The thing with shuttle is that they’re cheap and disposable. Putting fancy expensive technology into them is the worst idea since the invention of the worst idea ever.
T3 mining ships: Another complete waste of development time. There are already good mining ships for every use case, including covert-ops stealth mining ships. What would a T3-version bring to the table?
Well, not much really. If they’re good enough, they’d soon replace most (with covert-ops subsystem, even the stealth frigate) other mining ships. Gankers would love those, though! Considering how expensive those dumb T3 miners will be.