"We're in pretty tough," said Johnson, part of the Canadian coaching contingent at the worlds that begin Sunday and run until Aug. 4 in Barcelona.
"We've got a new group of kids coming around, and we're just hoping to be able to improve from the selection moment into the world championships. And then once they get there, to be able to convert any morning (heat) swims into semifinal or final swims."
Past Olympians Brent Hayden, Annamay Pierce and Julia Wilkinson have retired, so Canada is pinning its slight medal hopes on a predominantly young crop of swimmers as a new Olympic cycle begins prior to the 2016 Games in Rio de Janeiro.
Many of Canada's swimmers are in their teens or early 20s, and several have been to the world championships and Olympics before, but most have yet to earn shots at medals.
"Qualifying for (semifinals and finals) is something that we need to be better at, and we've recognized that coming out of the (2012) Olympics," said Johnson, noting Canada only had seven Olympic finalists.
Savannah King, 21, of Vernon, B.C., is among the young hopefuls looking to step up to the podium as she competes at her third world championships in freestyle. A member of the national team since the age of 14, King is looking to excel after she struggled for "a few years" to become dedicated to competing at international competition.
Bigger than most kids as a teen, she also had to overcome bullying and taunts because of her size and chosen sport.
"It's hard to be this dedicated to a sport, especially in your teens, especially when you want to be out doing other things," said King. "But it's just the highs you get from it that make it all worthwhile, and the training seems like nothing after those great moments."
She will compete in the 400 and 800 women's freestyle events and 4x200 women's freestyle relay. The worlds, King suggested, will be a chance for Canada to show its developing strength in the pool.
"We have a young team," she said. "There are a lot of young swimmers that are coming up in the ranks and showing that Canadian swimming is not all just high-level athletes that are older and retiring. It seems that we have younger athletes that are coming up and swimming faster than the previous generation. It's really good to see in the sport."
Toronto's Brittany MacLean, 19, is also looking to build on her international success after she earned her way on to the freestyle relay team that placed fourth in London.
The University of Georgia student has battled a nagging shoulder injury and pulled hamstring this year, but she helped Canada win bronze medals in the 4x100-metre and 4x200-metre relays at the 2013 Summer Universiade in Kazan, Russia while placing fourth in the individual events over the same distances.
"Right now, my body is holding up as good as I could ask it to," said MacLean.
Tera Van Beilen, 20, of Mississauga, Ont., hopes to contend in her first world championships. She qualified for her first Olympics, the London 2012 Games, with her best finish a ninth-place showing in the 100-metre breaststroke, before reaching worlds.
"My goal is to make top eight," said Van Beilen, who is slated to compete in the 50, 100 and 200-metre breaststroke events in Barcelona. "After a disappointing Olympics, I think that's a possibility for me."
Katerine Savard, 20, of Cap-Rouge, Que., also hopes to bring home a medal after winning gold in the 100-metre butterfly and silver in the 50-metre fly at Universiade.
"I had a great chance to see where I was at this point in the year," said Savard. "And, I think I saw a good thing, and I hope to be faster."
Savard will compete in her second world championships after missing the final in the 100-metre butterfly by a tenth of a second in 2011. In June, Savard broke her own national record in the 100 as she posted a time of 57.40 seconds, the second-fastest clocking in the world this year.
On the men's side, Ashton Baumann, 20, whose father Alex won two individual medley gold medals in the 1984 Olympics in Los Angeles, will be one to watch as he competes at the worlds for the first time, in the 200-metre breaststroke.
Ryan Cochrane of Victoria, 24, who won silver and bronze in the 1,500-metre freestyle in the last two Olympics, respectively, is one of Canada's few medal threats.
He has won four medals over the last two world championships, with two silvers in the 1,500 and a silver and bronze in the 800. But he has struggled in the 400, in which he placed ninth in London and fifth at the 2011 worlds.
As a result, he will use these world championships to gauge his progress after focusing on the 400 in training.
"We made a change, and I'm pretty satisfied with the results I've seen so far," said Cochrane. "It's something new, and I feel it's exciting to utilize that going into the world championships."
He is also thrilled about the potential that Canada's youth movement has to offer.
"For a long time, we depended on the older swimmers on the team to drive the direction of the team," he said. "It's exciting that the younger athletes can have the opportunity to be leaders."