It worked for the Dark Knight. 
Its time to let a new generation of kids grow up with Peter Parker.
Whats next, geriatric Spiderman? Course not...take him back to who he is.
It worked for the Dark Knight.
Is there something wrong with a next-generation Spiderman? We were treated to Peter coming of age and marrying... can’t they keep their marriage and the storyline? Seems to me they could... with a more talented and open-minded script.
How juvenile is it to revert your character to high school geekiness in order to “keep him fresh”. It demonstrates an immature worldview. If your character is getting too mundane, pass the torch. Can his spider powers pass to his kids? Can he, the great scientist that he is, duplicate the process that gave him his powers? Enhance them maybe? Screw it up and create something unpredictable? Lots of possibilities.