A dear friend I've never met but have come to love through social media is leaving her blog for personal reasons. She's not alone in this. Others have made similar announcements. Writers often start blogging as a way to promote their books, and then find that it takes more time than they have to give.
My friend started hers after her book was accepted for publication. It worked for her.
In the Mirror: A Memoir of Shattered Secrets by Ann Carbine Best has been out a year and still selling well, consistently showing up on Amazon bestseller lists, especially "Memoirs and Biographies" and "Marriage." Ann's social media efforts got her book off to a good start. Now it sells well regardless of her online marketing efforts. At this point, stopping her blog probably won't affect sales of her memoir.
There's no question that a strong social media presence can help jump start one's book with online sales. Is it enough to sustain best-selling status? I don't think so. Eventually, the book has to find an audience outside one's blog followers. Once it does, the writer can focus more on getting the next one written and less on promotion.
Ann is at this enviable position with her memoir. Although I'll miss my online association with her, I'm glad that her book is at a place where it doesn't need a blog to sell.