Well, for one, they could stop doing origin stories on well established characters. For example, the next Spider-Man movie will supposedly be a non-origin story

Well, for one, they could stop doing origin stories on well established characters. For example, the next Spider-Man movie will supposedly be a non-origin story as it is rebooted to be part of Marvel's cinematic universe. If they wish to start a new actor as a character it doesn't necessarily mean a reboot of the character. But issuing new actors over-and-over with reboots and origin stories for these characters would be the boring part. I, for one, like seeing the new heroes being introduced into the mix such as Guardians of the Galaxy and Ant-Man. Marvel has a large number of characters to rely on that haven't been introduced into the cinematic universe. Just because they are relatively unknown doesn't mean it won't work. Guardians was considered a risk because most people had no idea what they were, yet it did big numbers at the box office. These stories can be told endlessly if they are done correctly. Not all of Marvel's characters are super-powered beings and some of the normal characters have interesting stories to tell. Daredevil on Netflix is a good example of this. It didn't even feel like a typical Marvel enterprise until the suit came into play. Up to that point it was an interesting drama with occasional action pieces. Agents of Shield is another; stories about mostly ordinary people dealing with living in this new world of super-beings and gods. Where comic book movies/shows go wrong is when they are created to be commercials for selling toys and the story comes second. So far, Marvel has avoided this. Hopefully DC can do the same. If telling the story is always the most important aspect, then these things can last a long time before they get boring.