Landmark Medical Center was bustling the other day, almost exactly five years after going broke. It's a bit of a shocker: Despite five years of court supervision (a form of receivership), five years of failed attempts to find a buyer, five years of multimillion-dollar losses, Landmark abides. That's an argument likely to be heard Tuesday, when a Health Department advisory committee holds its first meeting on the proposal to sell Landmark to Prime Healthcare Services, a for-profit 18-hospital chain based in California. The stakes are higher than ever for Landmark. A previous prospective buyer won state approval but walked away, leaving the hospital with limited options. A statewide planning committee produced data showing that within four years Rhode Island will have about 200 more hospital beds than needed, at an estimated cost to the healthcare system of $100 million. Only half the people in Landmark's service area get care at Landmark.