By "Hacking", I mean coming up with a long term solution to elevate HACs from their vanishingly small niches and move them into the realm of viable fleet doctrines.
To be blunt, there is no good reason for flying a HAC over other vessels now. There roles were already precarious prior to Inferno, and the advent of the Pocket Battleships with their decent agility and high firepower combined with Retribution's vastly improved Tech 1 cruisers have squeezed the gap so much that paying 160 million ISK for a Vagabond hull seems ludicrous when Stabbers go for 6 million and Tornadoes go for 60 million. Why would you pay 100+ million ISK for a ship that has only slightly better survivability and damage?
The answer is, of course, you wouldn't. Unless you have the ISK to waste (and a lot of people do) or you need a rare specific role filled (like an Eagle sniping to 200 km), generally speaking the Tech 1 cruisers and battlecruisers are going to do the job.
THE OBVIOUS "SOLUTION"
"So?" you say. "Increase the damage and tank to a point where its worth spending the extra money and call it a day."
Well, that is one approach... but it has some serious drawbacks. For one thing, you get a huge jump in the power creep curve. Boosting the Tech 1 cruisers made them viable alternatives in PvP; boosting the Tech 2 a similar amount would thus negate all the work done on the cruisers and put you back in the situation where in order to be competitive a players needs to upgrade to be in a Tech 2 ship. That runs counter to the long term goal of tiericide and rebalancing ships where every ship has a good reason to be used.
For another thing, you create a ripple effect where Tech 2 logistics, command ships, heavy interdictors, and recons also need to climb the power curve to remain relevant in the new meta that would manifest itself in the environment the improved HACs would create. This would completely undo all the work done so far in Tech 1 ships.
Long story short, significantly boosting the damage and tank of the HAC class is not desirable and would create more issues than it would create.
A BETTER APPROACH
We've established that the Tech 2 cruisers cannot be boosted in tank and damage to far beyond that of their Tech 1 counterparts. That's not to say they can't have more damage and more tank; indeed, I think 15%-25% more damage and up to 25% more EHP is not unreasonable (numbers subject to change) and most of this bonus will typically come from some of the four bonuses that Tech 2 cruisers receive.
I think that we should look at other stats to mildly boost as well. For instance, the Deimos speed with a MWD is slower than that of a similarly fit Thorax (1900 m/s to 2200 m/s) and has one less mid slot (but extra high and low slot) making a shield tank harder (read: impossible). With some minor changes, we can make it so that the Deimos is as fast and tanks better to go along with its ability to fit the bigger weapons easier.
But is it enough? I say "no", its not enough to justify the price tag. Thus, I turn to Assault Frigates.
Assault frigates are in a very similar position: you don't want them to massively outperform Tech 1 combat frigate or else the latter will become obsolete in PvP, but you do want to justify their increased cost so that players have a choice to make between cheap and effective Tech 1 frigates and expensive but more powerful Tech 2 Assault Frigates.
The solution that CCP hit upon this past year was simple and effective. Assault frigates got a role bonus of 50% decrease to signature bloom from MWD. This made them superior to Tech 1 frigates in the role of heavy tackle and damage from a frigate based platform. We also know that CCP has reinforced in their efforts the concept that Tech 1 is general purpose ships, Tech 3 are super flexible, and Tech 2 is highly specialized. This is aptly demonstrated in the dev blog that discussed ideas for Battlecruisers, Tech 2 Command Ships, and Tech 3 Strategic Cruisers with the Warfare Link Processing subsystem.
Back to HACs. We know that being Tech 2 they should be more specialized than their Tech 1 counterparts when performing their specialized role. What is the specialized role? Well, the name gives it away now doesn't it? Heavy Assault Ships: like Assault Ships, but heavier.
Therefore I'm going to propose that along with making the Tech 2 cruisers slightly beefier and harder hitting versions of the current Tech 1 cruisers, they should receive a role bonus to reduce their MWD bloom by 50% just like the Assault frigates. This will help to make them very specialized at hitting harder and faster while surviving longer.
I do not envy the next phase of CCP Fozzie and co's job. Rebalancing cheap frigates and cruisers that hardly anyone uses is easy compared to changing some of the most loved ships in the game, especially considering one design philosophy misstep can undo the work of the past year. But the excellent and well received work done so far has given me hope that the future of PvP in Eve is in the right hands.