That's realistic, also in terms of match fitness. Gundogan was back on the pitch after 9 months.
I only hope that wild boy Mendy isn't tempted by the World Cup (injury was 23 Sept).
I've just found a Times article in a French source from 18 Nov, translated back to English:
""Benjamin Mendy will be unavailable for six months. The left side of Manchester City was on a positive dynamic. Sadly released on injury at the 29th minute against Crystal Palace, the French international suffers from a rupture of the cross ligaments of the right knee. However, the player explained to the Times that he hoped to play again before the end of the season:
"I told Pep Guardiola after I got my test results that I only accepted the surgery if he promised me that Manchester City would be in the (CL) semifinals when I came back."
Being a player of a remarkable season with the AS Monaco, his performances had opened the doors of the French team. Despite his injury, Benjamin Mendy does not forget the 2018 World Cup in Russia:
"I want to return as soon as possible, I want to play in the Premier League, in Cups, in the Champions League and I have no doubt that I will be playing the World Cup." he told the Times.""