The 36 year old, who will be back for City's Boxing Day Trip to Cardiff City after serving a one game suspension, is taking things on a year by year basis.
Speaking to the Sunday Mercury, Boothroyd said about Carsley: "Lee wants to work year to year and I think that's very sensible. "But for me he can easily play another two years. He's got an awful lot going for him - his attitude is first class and he's one of life's leaders.
"He has massive respect from all the players - us and the opposition.
"What he brings to your club and your dressing room is a professionalism and a nous of how to win. And that's a very important facet of any club that wants to be successful.