My old purple coneflowers have been very long lived- like 20 years. Some of the newer vegetatively propagated ones are not very long lived for many gardeners, including me. Cheyenne Spirit is a recent release which I hope will do better. It can be grown from seed so, at least, if one is lost, it's not such an expensive loss. Seeds are pretty cheap. I started some last year and have another batch for this year.
Karen