Good news. I had my hip replaced about the same time. Maybe a year earlier. I often now think about how many more years I have before a revision, five, 10, never?
I am not built for ultras, more of a fast twitch runners, was fast over 800m as a kid. But I have always enjoyed volume, so well before hip issue enjoyed week after week of 70-90 miles per week, a couple of 100s. I am not there yet. I am about 40-45 miles at this time. would like at least one more aerobic base-building summer, coming up here. And would be happy to run some 70 mile weeks.
Glad to hear that people like yourself are running ultras….there is hope.