James McCarthy, Robbie Brady and Jeff Hendrick have all made the step up to the senior team in recent times after impressing in the junior ranks, and King is urging is current crop to use the new European Championship qualifying campaign to do the same.
The manager, whose side faces Group Six favourites Germany at the Showgrounds, Sligo on Monday, said: "We have had two players progress to the senior team recently, young Robbie Brady and Jeff Hendrick, who are eligible to play for us, and it is great to see them going forward to Giovanni Trapattoni's team.
"Maybe one or two more could follow them. I never like to highlight players, and it's not my job.
"It's the senior manager's job and he will do that in his time, but it's good for my players to aspire to that."
However, while exposure to international football in the Under-21s may prove the ideal grounding for the big stage, King is adamant that developing potential for Trapattoni is only part of his role.
The Republic finished third in their group during the last campaign and having beaten eventual finalists Italy on the way, have high hopes of improving upon that this time around.
King said: "My role is to identify them and expose them to international football and see how they manage it.
"But it's not just about playing games. They want to play and they want to win games - that's human nature - and that's what we will be trying to do."
That may prove easier said than done on Monday with the Germans heavily fancied to top the group.
Ireland currently hold that honour by virtue of goals scored with both they and Germany having won in the Faroe Islands in their single fixtures to date.
However, German manager Horst Hrubesch has an enviable array of talent at his disposal and King knows just how difficult it will be to get a positive result.
He said: "Everybody who is in football knows the quality of the German set-up. They have been setting the standards at throughout the age groups for years.
"It's going to be a tough, tough match against great opposition. But anybody who is involved in football relishes the opportunity to test themselves against the best, and our players will be coming up against some of the best Under-21 players there are.
"We have got a valuation of some of their players and the value of their group is just astronomical.
"They could field two of three teams in this age group and be competitive, so it's a great test for my players."