I think she does owe long time fans a reason but they need to cancel their memberships if they feel she is not putting out the content and web-cam shows she agreed to do. Is the subscription websites still lucrative? I don't know anyone who pays for that stuff anymore.
She seems to have retained a staunch bunch of fans that remain faithful members to her website. But I'm completely sure that membership has been dwindling for a while now.
Regarding owing anything to anyone, I think you are right. She should show some respect to people who have been long time fans of her and come clean as to why she's such a slacker lately and her scarce updates and cam shows are less and less frequent and their quality is so low, compared to what we used to see before.
Like mmaphd said, if she is to retire she should go out with style. :2 cents: