One of the names mentioned has been Taron Egerton who recently starred in Kingsman: The Secret Service, directed by Matthew Vaughn which is also based on a comic book series by Mark Millar.
It's not just because he is British. Lots of America's top superheroes have been played by Brits (Batman = Christian Bale, Spider-Man = Andrew Garfield, Superman = Henry Cavill).
It is actually due to an interesting trivia fact that proves that Mark Millar comic book adaptations are the proving ground for future Marvel and D.C. Heroes.
Example 1) Wanted (2008)
Millar's first comic to be adapted for the big screen was Wanted which starred James McAvoy in the lead role of Wesley.
McAvoy would go on to play Professor Charles Xavier in X Men: First Class and X Men: Days Of Future Past.
The first Kick-Ass film was directed by Matthew Vaughn (who would also go on to direct McAvoy in X Men: First Class) and starred Aaron Taylor-Johnson as Dave Liewiski and Evan Peters as his friend Todd.
Evan Peters would play Pietr Maximoff aka Quicksilver in X Men: Days Of Future Past and Aaron Taylor-Johnson would play Quicksilver aka Pietr Maximoff in the upcoming Avengers: Age Of Ultron.
Vaughn's 2007 film Stardust starred then unknowns Charlie Cox and Henry Cavill...
It would be fair to say that based on the evidence they have that adamantium touch when it comes to spotting superhero potential.