Trevor Bayliss, the England coach, has challenged the next generation of England players to stake a claim for a spot in the 2019 World Cup squad although he expects most of those who took part in the Champions Trophy to be around for that tournament.

Bayliss has often spoken about the four-year plan to build to the 2019 World Cup, with the Champions Trophy seen as a stepping stone, but the manner of England's one-sided exit against Pakistan will be a dent to the confidence of a team that had surfed a wave of run-scoring.

Only two of the current squad are over 30 - Eoin Morgan and Liam Plunkett - and though there will be the natural fluctuations in form - as witnessed by Jason Roy over the last few weeks - and injuries will occur, Bayliss is keen to use the next two years to build experience.

The first opportunity for new faces to have a taste of the international scene will be the three-match T20 series against South Africa with the squad including five uncapped players: Dawid Malan, Liam Livingstone, Tom Curran, Mason Crane and Craig Overton. The one-day series against West Indies which finishes England's busiest ever home season could be another chance to assess the depth on offer.

"I think we'd be remiss if we just said these 15 or 16 guys are going to go to the World Cup in two years' time," Bayliss said. "We've got to be sensible about it and if there is someone else who deserves to be in the team then we've got to look for that.

"We've got the Test guys having a rest here so they'll be able to play in the county match before the Test match which allows us to play some new guys and you never know, if one or two of them come up with the goods, they could find themselves in the team in two years.

"We've come a long way in the last two years and, like the fans, we'd like to win every game we play in," he added. "But the simple fact is we are still an improving side and getting to a state of play that we think we're capable of, but these guys are mostly 26 or 27 so they should be around for another five or six years."

During the Champions Trophy, England only made two changes to their team. Adil Rashid was surprisingly left out of the opening match against Bangladesh, and then Roy's lean run become too much to accommodate and he was replaced by Jonny Bairstow for the semi-final. Roy is part of the T20 squad to face South Africa and Bayliss had encouraging words for him.

"I think you'll see Roy at the top of the order a lot more for England. It was one of those situations where you've got one guy hoping to score runs and another guy who, when he comes in scores runs and is trying to prove a point, so there was a little bit of the negative-positive thing there. [Bairstow] batted reasonably again there, getting 40-odd."

Joe Root, Moeen Ali, Ben Stokes, Jake Ball and Rashid have been left out of the T20 squad to enable them to play in the pink-ball round of County Championship matches at the end of the month. While Root, Moeen and Stokes are certain to feature in the Test side, it could mean that Ball and Rashid are also in the mix.

Jonny Bairstow, the Test wicketkeeper, will miss the final T20 but Jos Buttler, who was part of England's previous Test side against India in Chennai, is available for all three matches. Bayliss said it did not mean Buttler wasn't in contention to retain his spot and he will go straight from the final T20 in Cardiff to Lancashire's Championship match against Warwickshire at Edgbaston.

"It is just he is so important to the T20 side," Bayliss said. "We are giving a rest to the guys who are definitely in the Test team, but a lot of the guys will play in that third match and then back it up the next day in the pink-ball game and he is one of those."

England's squad for the first Test against South Africa at Lord's is due to be named after that round of Championship matches.