Sirotkin may have been on the short end of the stick as Williams will field an all-new driver line-up in 2019 however he admitted that his time with the team was a positive one and that the changes in rules could help the Grove-based team on their road to recovery.
"This year, the rules are changing so you could say that the chances of the teams are levelled," Sirotkin told Izvestia newspaper.
"No one will initially have an additional advantage, which makes it possible to improve in some areas and be competitive.
"I only want to wish Williams good luck. I spent a year in the team, putting a lot of effort into the development of the car, and so I hope that, despite a number of internal difficulties, the team will develop.
"I am not sure that will be so vividly visible from the results. At the same time, he expects Mercedes to remain at the front, but with the regulation change, "It will be very difficult for them to maintain the leadership".
"I think that this will be the most difficult season for Mercedes of the past five years."
Sirotkin will be racing for SMP Racing in the World Endurance Championship Super Season in 2019.