Pep Guardiola's side edged out Liverpool for the Premier League title last season, with the Red Devils meanwhile finishing sixth - 32 points shy of their cross-city rivals.
City could now claim the league for a third straight time this coming season, but Robson suggested the loss of a leader like Kompany could see them struggle for direction.
"There’s always a chance of catching a team that’s just won the league," Robson told Goal.
"It depends on City with how they replace Kompany because he’ll be a big miss for them, he was a real leader in the dressing room. It also depends how you start the season, if you start it off really well you can be confident
"City have definitely got the ability to go win the league again but they're definitely catchable as well."
Kompany, who has been with City since 2008, departed the club at the end of the season to become player-manager at Anderlecht.
The 33-year-old has left some big shoes to fill according to Irwin, who is all too aware of the gap that separated the two Manchester clubs last season.
"City have been fantastic the past couple of seasons and Kompany is a big figure for them, so losing someone like that with his strength in the dressing room will be a big loss," Irwin told Goal.
"But they’ll still be a hard side to beat and there was a large points gap between ourselves and them last year so it’s up to us to rise up to the challenge and start the season really well."
The Red Devils are currently without a recognised club captain after the departure of Antonio Valencia with Robson confident Solskjaer will make the right choice.
"Only Ole can decide that, he’s inside the camp everyday and sees who can influence the players on the training ground and on the pitch," he said.
"I think once he gets to know the players a little bit more he’ll make his decision on who he wants to be club captain."