Clarke was speaking on his first visit back to Scotland following the qualification-sealing 4-2 win over Denmark last month.
“The number of well wishers that are genuinely excited that the country’s qualified for a World Cup is great,” Clarke said.
“It shows you the power of football and what it can do for people.”
Scotland hope to organise friendly matches against non-European nations including a send-off game at Hampden.
Clarke is also planning two training camps, including one in a hot climate, before the squad travels to its as yet undetermined training base.
“The squad size will be 26, so that gives you a little bit of leeway,” he explained.
“Obviously, I’m very loyal to the players that have got us there. That’s not a big secret anymore. People know how I work. Those players that I’m loyal to also have to play well, they have to get their minutes on the pitch that make them an easy pick for me but there’s always space for someone else.
“I’m not afraid to bring younger players into the squad, I’m not afraid to change one or two players if that’s what has to be done.
“There’s still plenty of opportunities for the players who feel they’re on the periphery. Their job is to go out and play well every single game, grab my attention and force their way into the squad.”