Some random thoughts...

A blanket EHP nerf across the board is a little silly. The raw HP levels are already out of balance between supercaps of different races. Reducing everyone by the same amount means we miss out on an opportunity to correct that.

Solution? Adjust HP levels as follows:
Aeon -20%
Nyx -10%
Wyvern -15%
Hel - No change

Avatar, Erebus, Leviathan - No change
Ragnarok +10%

Supercarriers fighter bays are a little anemic. These ships are tricky and time-consuming to refit, so carrying a single flight of their only damage tool seems like a recipe for disaster.
Solution? Let them carry ~30 fighters/bombers.
Alternatively, remove the in-built drone deployment bonus in Supercarriers but increase the number that can be deployed using Drone Control Units. This introduces a trade-off between raw damage and remote-rep ability, as well as an increased risk of losing all your bombers in one flight or deploying less but having spares available.

There isn't enough difference between Capitals and Super-Capitals. Carriers have a role as support and anti-subcap ships, as escorts for Supercarriers that are now unable to defend themselves with their own drones. After these changes Dreadnoughts will still be limited in use as they're still just as vulnerable to being one-shotted as before. If you have enough titans, there will be little reason to use Dreads.
Titans also remain overpowered versus subcaps. With tracking links, remote sensor boosters and enough supercarriers behind them, beating a titan blob simply comes down to having more titans. Beyond a certain threshold subcap numbers still do not matter.

Solution? Three actually:

1) Doomsdays balanced on sig radius - A blanket 'no DD on subcaps' rule seems a little anti-sandbox for me. If I want to burn half my isotopes picking off Rifters, why can't I?
Let's change Doomsday damage to scale on target sig radius. For example:

Supercap = full damage
Dreadnought = ~1mil damage (with DD Op V)
Battleship = ~50k damage
Cruiser = 5k damage
Frigate = 1k damage

It will no longer destroy ships outright (unless they're nearly dead or terribly fitted) and makes Dreads more cost-efficient at taking on Titan fleets, increasing their role. This is also great to help smaller groups fight larger ones using their insured dreads.

2) Jump 'Calibration' - Supercaps should have a delay in order to lock onto a player-activated cyno beacon. This time is based on the distance they are travelling, so while a 2ly jump might take five seconds, a jump to the full range could require 30 seconds to lock on. This has several effects. Firstly it means that supercaps planning a hotdrop need to be nearer the target, increasing the odds of them being spotted. It also increases the odds of the cyno and/or tackler being destroyed or jammed before support can arrive. Finally it gives regular capitals an increased role as 'rapid-response' capitals, able to move around faster than their larget counterparts.

3) Electronic Attack Frigates. Yup you read that right.
This diminuitive vessel rarely seen outside of alliance tournaments and hilarious lossmails could use a bit more of a purpose in life. In the same way that HICs bypass the supercap immunity to tackling, EAFs should bypass their immunity to ewar.
The best part about this change is that it balances itself:
EAFs are already made of paper, which means that any supercap fleet with a supporting fleet of any description will be able to swat them down with ease. It provides a counter to the exponential remote-repping and tracking links of hundred-strong supercap fleets, especially when faced under a cynojammer. Plus of course it opens up an avenue for the Eve Newbie. Remember that guy? Well now he can be taking on the big boys in a few short weeks of training, helping to make a difference to that fight.