A friend of mine has oaks that have died very quickly. Crown half or mostly dead over one year, then didn't leaf out the next, and bark was already falling off early that year. A branch went through their roof too. They got someone to fell it. I learned how fast one can die. 40+" of solid oak too.Wow, look at that stump log!
I had a similar situation but with a much smaller tree, it was stone dead, bark falling off dead, leaning over a fence and the neighbours above ground pool. They told me it only died recently, yeah, right...
I bid the job but put in a liability waiver clause because it was so unstable...someone else got the job, no longer my worry.