I'm not so sure. Like many other posters I thought Sam or Bucky would pick up the shield. But Coogler mentioned wanting to introduce Elijah Bradley into the Black Panther film, and having a descendant of someone who went through a twisted version of the super soldier program take on the mantle would be interesting.
And billionaire, philanthropist playboy Tony Stark must have a son or daughter out there wanting to step into the shoes of the father they never met.
I'm thinking Feige and company will wait a respectable amount of time, but at some point we will see legacy versions of Cap and Iron Man, and perhaps Hulk (Jennifer Walters?) and Hawkeye (Kate Bishop?) as well.