It is my contention that the biggest problem with DC and Marvel super hero comics is that no heroes ever age.
At one time the idea by DC was to keep ever super-hero at age 29. That was around the era when we heard don't trust anyone over 30 and Logan's Run was made into a movie. Also it was during an era when the average age of a comic reader was probably between the ages of 8-15 years old. It was assumed that an average reader would only read comics for a few years and move on to other endeavors. As the vast majority of the readership was male the new endeavor was usually girls.
Given that as a back ground never aging heroes and recycling old stories was not only okay it was easily done as a small switch and updating done here and there any story seems new again to a new audience.
Marvel came into the game in the Silver Age and eventually upped the ante. Spider-Man gets his powers at 17 years old and by issue #28 has graduated from high school and will be on his way to college. Reed Richards and Sue Storm get married and have children. Giant-Man retires from the super-hero business. All of sudden comic book characters have real continuity and things actually change. Marvel's growing sales forced DC to follow suit to some degree.
Once Marvel became number one, it has been stated that Stan Lee stated no more changes to the character just the illusion of change. No one thought that these characters would be already for forty plus years.
This means that a character like Cyclops has gone from being a lonely orphan to having two super powered brothers, a father who is an outer space pirate, has had two future children come back, has been married to Jean Grey, a clone of Jean Grey and was sleeping with the Phoenix force and is now hanging with the White Queen, has died and been resurrected and is portrayed as around 30. The weight of his continuity makes it harder and harder to find his character believable. Plus with Marvel's sliding scale of continuity (only 10 years of back history) we have no idea what is in his actual history and what is not in his history.
DC has the same problems and actually seemed at one point like they were wiling to move on, then Oliver Queen's soul was brought back from heaven and put into a ten year younger clone of his original body. Hal Jordan is brought back from the dead and we now have the same heroes as the main stars as opposed to the next generation. So when we do Ollie as a "man of the people" we are doing the same story with the same guy.
If you allow heroes to age you can get more interesting versions of the characters and have more of a blank slate to write their history.
Look at the JSA, the new Mr. Terrific is more interesting then still having Terry Sloane around.
This should be done with the Icon characters also. Look at Kingdom Come, Bruce is great as a master manipulator in the background. Dick could be Batman and married to Babs. The natural progression of these characters almost create stories that write themselves.
Once you go that route as a reader anything could happen and each issue is an exciting adventure that means something to the character.
Let Iron Man retire, he should be around 65 years old and should have protegeee or son that is taking over the armor, instead of moving his history forward.
When you want to keep a character around and let them age very slowly, give them a super soldier formula or have them bombarded with cosmic rays.
The time has come for this to happen because the fan base is staying with these characters forever and will slowly leave these books when they tire of the same story over and over. So many fans are jaded and are hanging on by love of the medium, but the time to let characters age (and it can be slower then real time) has come or the industry will slowly fade away with the fan base.