While they definitely look sexy; there are no extra tech 3 ships planned for now. Reasons for that are quite simple.
First, you need a role for them that can fit in our balancing composition while not making existing vessels obsolete. That is a big problem we face with current Tech 3 cruisers, best example being the Tengu / Tech 3 command subsystems being better than tech 2 counterparts, while the others tech 3 cruisers / subsystems are quite subpar. Before we introduce new tech 3 ships, we really want to define a purpose for them that is unique and revamp existing ships to match. Ideally, each of their configuration should be useful, but it is not the case in practice when only a few have practical applications.
Second, frigates are not really the best hull to base a tech 3 ship hull from. That's because tech 3 ships are, by nature, expensive to acquire, which conflicts with the frailty of a frigate as a whole. Frigates are supposed to be expendable and relatively straightforward to set up, but this directly clashes with the complex nature of selecting and getting subsystems. Also, frigates have a lot of variations already - navy, pirate, tech 2, you name it, we have it. Thus, the chance that a tech 3 frigate would bring something new to the table without creating the problem explained in the first paragraph remains very low, and we would setting ourselves up for the same problems we face with tech 3 cruisers at the moment.
Based on all of this, here is the ship priority plan for the time being:
- Fix old hulls that are underpowered
- If and when we need new shinies, create new tech 1 roles (tier 3 BCs) or, if needed, missing tech 2 variations
- If we ever need new tech 3 hulls in the future, my vote would be to larger hulls, like battleships for the reasons explained above. Tech 3 battlecruisers are not a choice I would vouch for however, as they would conflict with tech 3 cruisers (same weapon system size) and without to say this ship class already is extremely popular, quite at the expense of the other hull sizes, so no need to aggravate the problem further.
Hope that clears things a bit.