The bad guys are the bad guys. Things continue much the same for twenty years or so and wallah add kids families and a new generation. So that is where we are.
More than a few good "What-ifs" will help you there. If you're looking for an alternate version of a character for a son or daughter of an established hero, I'd recommend using one of the variants. At some point, Marvel decided that their core universe was the '616' universe, which is core continuity. Every time they create an alternate future/past/current reality, someone pulls a number of the air and slaps it on there (though it may not be mentioned in the comic). For example, someone decided that the Avengers TV show that is currently running is actually
Marvel-80920. It seems like Marvel is trying to get several of their animated projects to mesh, similar to the way that B:TAS, S:TAS, Batman: Beyond and JLU all did.
As for comics...well, there's been a lot of water under the bridge, but the recent "Heroic Age" event appears to mostly have been designed to undo a lot of the continuity messes of the last decade. Heroes are no longer fighting each other, everyone is becoming friends again and many dead heroes are back. The biggest change from comics of 20 years ago is that the X-men finally gave up on rebuilding Xavier's again and again and have relocated to San Franscisco Bay on the remnants of Magneto's old Asteroid Base that they've renamed Utopia.
If you're looking for some good teen superheroes, the Young Avengers are some of the best. Each one, when first introduced, appears to be aping an existing Avenger...then we discover that each one of them actually is related to ANOTHER Avenger, through some clever slight of hand (The Asgardian and Hulkling, for example, aren't related to Thor or the Hulk).
For completely new characters, let me spitball:
Shadow and Light (Melissa and Jamaal Johnson): Son and Daughter of the superheroes Cloak and Dagger, Shadow and Light share their parents powers, but in reverse. Raised by their parent to be rules-followers, this has not left them humorless, but reluctant to break the rules, ever. Melissa uses her Shadow and teleportation powers without hesitation and often rushes in blindly to danger, leaving her more reserved and analytical brother to use his light daggers and healing powers to bail her out. Despite their occasional sibling bickering, they are very close.
The Quantum Mechanic (Joshua Stark): Son of Iron Man and Madame Masque, Joshua is a genius with machines, getting them to do whatever he wants. His parents are divorced and his resentment at this has lead to a rebellious streak. He spends a lot of time pulling pranks and defying authority, though he's a loyal friend.
Sawfish (Kevin Newell): Son of the hero Stingray, Kevin is a bright optimist who is a bit naive. Highly athletic and adventurous, Kevin worked with his father to create his own armor suit. Designed for deep-sea diving with his father, his suit grants him super-strength and endurance for high-pressure work. Unlike his father's suit (which can zap with electicity), Sawfish has a retractable saw built into one arm for cutting work (hence his name) an advanced array of sensors.
Diamond Girl (Danielle Jones): Daughter of Luke Cage (Power Man) and Jessica Jones (Jewel), Danielle's skin is as hard as her fathers. Virtually impervious to harm, Danielle also has the ability to project energy bolts from her hands. As the daughter of two Avengers, she's seen a lot of superhero action in her time but finds the whole thing somewhat boring. She's motivated more by a desire to impress her loving parents than any real interest in being a superhero, but she does genuinely want to help people. Danielle spends a lot of time acting indifferent and slightly snarky, but when real trouble arises, she leaps into action with the experience a lifetime of being around superheroes provides.
Ultron-15.C (none) - An Ultron clone that was hacked by Hank Pym and the Vision, 15.C was templated off of the Vision, but with his memory wiped clean and with a new emotional matrix installed. He has an extensive memory, with a large swatch of the Avengers data files in his head. While he is made of adamantium, he has been mostly de-weaponized, except for some stun beams. He is reserved, uncertain and anxious to prove he is a hero and is not like his 'fathers'.
How are those?
