jemima responded to my earlier post on what makes a successful blog with one of her own here. One thing I forgot to add earlier is, you* have to want to blog and you have to like blogging exclusive of any interaction from others.
It's the same as writing fic and posting it online; if you're not writing for your own intrinsic satisfaction, if you're require the hallelujah chorus every time you get up on the blogbox, then chances are, your blogging career is going to be short-lived. There are a gazillion blogs out there and maybe 1 or 2 percent get a huge audience; chances are, you and me are not among the lucky percentage, in which case the motivation to blog has to be from within.
My personal view on FB these days is that it's an extraodinary event and ought to be treated as such, whether it's here in the blog or on my stories. Either way, the existence -- or lack thereof -- isn't going to stop the blog from churning out Seema!propaganda because I like blogging and I want to continue.