I suggest a similar revamp as you do (Techsy), but I would go a different direction that doesn't alter or disrupt the scale of the game in any way as my major solution:
1. Remove hull types entirely - It's already a mechanic which has become completely overshadowed by valuing a unit by its particular stats and immunities anyway. The few times it does come into account could be made infinitely more intuitive in another, less complicated system.
2. Rework the armor system to something that has a huge impact on the game the way armor/shielding would within actual space combat.
3. Combine armor and hull type into a single mechanic known as "Armor Class". Fighters, being fragile and having relatively little to no armor would be in an Armor Class of zero, while Frigates, for example which in the Sci-Fi Universe are typically like minituarized starships, might have an Armor Class of 4 (Armor Class 6 is the highest).
4. Each Armor Class would offer a flat 15% damage reduction to all damage types, stacking cumulatively, while each point of Armor Penetration would ignore one level of Armor Class.
5. As an example, Fighters have an Armor Class of zero, and an Armor Penetration value of one. However, their cap DPS is huge. This means that any ship with relatively little armor (such as Bombers) are automatically weak to them. However, ships like Frigates, with a higher Armor Class, resist their attacks. In the same way, Bombers, with a notoriously high Armor Penetration (sticking with the Sci-Fi Universe standards again) would be a great counter to Frigates. The triangle still exists, it's just infinitely more intuitive than before, and makes more sense.
6. Remove the area of effect immunity from Frigates and give them to Fighter Class ships. This makes overwhelmingly more sense. A fighter's small size and high maneuverability would give it the ability to dodge obstacles and attacks their larger counterparts could not. Giving high cap, high damage units such as Fighters immunity to aoe fixes the high cap vulnerability problem almost immediately and makes more sense.
7. Take the vast majority of immunities out of the game and use unit stats and the new armor class mechanic to rebalance the entire cast from the ground up in unique and creative ways, since all the mechanics are suddenly useful again.
Let's look at the "Anti-Crowd Control" Roster I mentioned before in my original post: MLRS, Electric Shuttle, Spire Railcluster, Lightning Torpedo Frigate, Grenade Launcher, Beam Frigate.
MLRS becomes the ultimate anti-swarm unit with high dps, multiple shots, and can clear out waves of the newly aoe immune Fighter class. Its ability to bypass the immunity with high dps is what makes it such a strong counter. However, the unit is weak itself with a low Armor Class.
Electric Shuttle still has an aoe attack so now it has become completely useless against Fighter Class ships. However, it has the highest Armor Penetration possible (existing mechanic made useful), meaning it absolutely wrecks bigger ships such as bombers and frigates clumped into an aoe. Totally new role.
Spire Railcluster gets an Armor Penetration of 3 and a medium DPS making it a unit decent against everything now, but not great against anything. Still low capped and without immunities it's a great fleet booster but lacking when compared to more specialized alternatives.
Lightning Torpedo Frigate similar to now, however its torpedoes can still be shot down, making it somewhat weaker in many situations to its cousins. However, it being a frigate it gets a high Armor Class, giving it more survivability than the alternatives.
Grenade Launcher now has a high dps, high cooldown between shots, and an Armor Penetration of 2 and its attacks ignore aoe immunity. However, the area of effect it has is still very small (as is currently the case). However, it is given a new mechanic whereby when it kills a unit (or units) with its attacks, they also explode, dealing the damage of the original shot to all the units around themselves. This can cause a chain reaction. This is different from the Saboteur in that it deals the damage of the original shot, not a percentage of the unit's health. This makes it more specialized against smaller swarms.
Beam Frigate, like its Lighting Torpedo counterpart, is also a frigate, giving it increased survivability in the field. It does massive damage and its attacks ignore "aoe immunity", but it has a low armor penetration and is limited to the specific number of units its attack can hit (I think the current number is 7). This makes it more reliable than the Lightning Torpedo counterpart in terms of crowd control, and more survivable than the MLRS in an engagement. However, its overall potential as a "crowd control" unit is diminished by the limited nature of its beam attacks.
Anyway, those are just a few examples of how totally revamping the hull type and armor system to something fundamentally simpler and more intuitive could actually make counters and roles more specific and give the game more depth than it has now.
Some people might call this AI War 2, but in actuality the game wouldn't change that much, the new mechanics would be extremely simple and easy to understand. The triangles would still be there. The only major difference is that the roles and mechanics which already exist would make more sense and come into play more often and the overlap would disappear.
