A small Bay Area hospital chain is scrambling to find a new buyer after a deal suddenly fell through this week, and it may eventually have to file for bankruptcy. A lone public hospital in San Pablo remains on the brink of closure, unable to find a buyer. Meanwhile, other stand-alone hospitals — like Children's in Oakland — are being scooped up by larger systems. The Bay Area hospital landscape is going through a shakeup, one that's particularly directed at independent medical centers or small chains that serve a preponderance of patients who are uninsured or covered by government programs.