Can you phase them out one at a time? Start planting a few sugar maples as soon as possible in an area near them. It appears as though your fast-growing shade trees are a temporary fix to something you'd like to be permanent. I would want to keep those trees as long as possible, only removing severely rotted or loose branches that may fall on adjacent structures; otherwise let them be, savor their diminishing shade and maple syrup, and plant the new generation if there aren't already some starts or shoots coming up around them.
SCB
