The Black Cats have been active in the market so far with five arrivals in the form of Patrick van Aanholt, Billy Jones, Costel Pantilimon, Jack Rodwell and Jordi Gomez.
They have also seen a number of players leave already with the likes of Craig Gardner, Phil Bardsley, Jack Colback, Kieren Westwood and David Vaughan departing.
Sunderland boss Gus Poyet is still looking on trying to add to his squad, and discussions with Liverpool over the sale of Fabio Borini are said to be still taking place.
And Johnson thinks that the squad is still set to undergo more cosmetic surgery ahead of the new Premier League season.
Speaking to the Chronicle, the former Manchester City winger said: “I think from now until the start of the season there will be a big change again – outgoings and incomings I would imagine.
“But as long as we can keep the basics of what we want to do as a team, I don’t think we’ll have any problems.”
Despite the Mackems' struggles last season, Johnson enjoyed a positive campaign on a personal level.
The wideman scored eight goals and contributed five assists as Poyet's side eventually finished 14th with a League Cup runners-up medal.
Meanwhile, Valentin Roberge has stated that he does not want to leave the club, despite featuring just nine times last term.
The 27-year-old arrived on a free transfer in 2013 but was largely used as backup throughout the campaign, but speaking to the Sunderland Echo, the Frenchman said that he sees his future at the Stadium of Light.
“Last year was good preparation for this year. I had to be patient, which was not easy," he said. "But it’s a new season and I just want to work hard and then see what happens.
“I hope to play more games this year. I don’t know what will happen with the manager’s decision. But all I can do is work, work, work.”
Poyet takes his side to West Bromwich Albion on August 16 to begin their new Premier League campaign.