Hamilton stunned the sporting world in February as he confirmed that 2024 would be his 12th and final season with Mercedes ahead of a move to the Italian team.
The seven-time world champion has endured a challenging start to his final campaign with Silver Arrows, failing to finish ahead of team-mate George Russell in any of the first five grands prix.
Leclerc was chosen over current team-mate Carlos Sainz to remain at Ferrari alongside Hamilton, but has also been outperformed during the early stages of the season.
“We’re all looking forward to that dynamic,” said Sky Sports F1 pundit Rosberg, who drove alongside Hamilton at Mercedes from 2013 to 2016.
“Nevertheless, Charles is probably the second-best qualifier out there after Max Verstappen, one could possibly say at the moment, so it will be a tough battle for both.
Hamilton’s decision to leave Mercedes came at the start of what looks set to be a third season where the team have failed to provide him with a car capable of competing for race victories.
While the Brit insisted his decision was primarily motivated by a “childhood dream” to drive for Ferrari, the Italian team are currently comfortably outperforming Mercedes.
While Red Bull remain the sport’s dominant force, Sainz led a Ferrari one-two at the Australian Grand Prix, while a Ferrari driver has featured on the podium at four of the five races this season.
“It came as a huge surprise,” Rosberg said. “No one expected it. But If you look at the grand scheme of things, then why not?
“It’s towards the end of his career. There are two legendary teams – Mercedes and Ferrari – and I know Lewis has always been a big fan of Ferrari road cars also, so why not make that switch and have a different experience of driving in red once?
“At the moment, it seems in performance terms to be the right decision for him, which maybe he’s made an amazing move like he did 12 years ago by moving from McLaren for Mercedes.
“McLaren was winning races and Mercedes was nowhere, and the moment he moved, McLaren went backwards and Mercedes started winning races. Maybe he can get the same timing done again.”