For the large part, Mercedes has been dominant, winning all but two races this season. However, Red Bull has won two out of the last four races, with Max Verstappen staking his claim as one of the top drivers on the grid.
Ferrari is yet to win a race this season, despite having three poles to its name, but this is something that Hakkinen can see changing during the second half of the campaign.
"They should be back in contention in Spa and Monza, where their straightline speed will matter, but it is clear that their car is just not competitive from race to race," Hakkinen said on his Unibet column.
"Not only have they been unable to beat Mercedes, they are now behind the Red Bull-Honda package in terms of competitiveness. The second part of the season should be quite different from the first.
"I expect Ferrari to be pushing really hard for a win in Spa and Monza, but Red Bull and Honda will also be continuing to develop their car and Mercedes cannot take their domination for granted any longer.
"We have just had four really exciting Formula 1 races and I fully expect we have many more to look forward to before the season ends in Abu Dhabi on December 1st."