This is just my opinion, but we have too many Heroes that don't have any real use anymore. In my personal opinion, it's time to start retiring some of them, if there isn't going to be a specialty mode made to take advantage of them. By retire, I mean delete. Entirely. All assets, all modes that use them get adjusted, etc.
What I'm suggesting is IGG check their usage data (I'm sure they have information on which Heroes get used most and least, since we had something similar in the stat event in the last anniversary stuff), and start cleaning them out.
However, do it in a fun way for everyone. Make a big event out of it. There are numerous ways you could do this, and I'm not suggesting this is the best or even a good way to do it. It is simply an example, though I'm sure there are much more interesting ways to do it.
For instance, do it something like the world boss. There is a monster that only three Heroes can "damage".
You contribute a Hero Card to register your chosen Hero for the battle. You get one sword per day, but can get up to three more by contributing more one Hero Card for each sword. In the fight, you can use up to six of that Hero from your altar to attack the monster, built however you like.
Once the monster is "killed" (it'd be on a timer, no damage caps), whichever Hero did the most damage will Heroically, but tragically, "die" in the process. In other words, the Hero most people chose to use will have been their vote on who to get rid of.
It would be like voting for the Hero you want gone and giving him/her one last hurrah as a sendoff and earning great rewards for the battle as well as 1.5x all resources used on all of your biggest Hero of that type and then a straight refund for all the rest.
So you get useable resources back, a bonus for your biggest Hero of that type, and the rewards for participating in the monster battle (which would be nice as well). You also get a bonus for every Hero Card you have of that type.
This lets you eliminate some bloat, get rid of Heroes you don't want to bother with any more like all those ones you skipped giving skins in favor of giving second skins to other Heroes, and gives us back the resources we wasted on useless Heroes.
There are tons of possible ways this could be done, but I suggest an interactive method be a requirement. Something that is fun, not a chore we have to do to get prizes. This also puts the choice of who goes in our hands, so it should eliminate at least some of the complaining... ah, who am I kidding.
Honestly, I'm only about half serious about this. I think a legacy mode would be better, as well as updating the existing Heroes to balance them and make them useable again. The balance thing is pretty much not going to happen, if we're honest. A legacy mode is possible.
This is mainly to get people tossing out ideas about ways to make retiring Heroes a fun and useful thing that might make it more palatable. Suggestions are welcome.
Move along, please.