A decade ago, when the newborn UPMC Health Plan was just beginning to crawl out of the red, it was fielding acquisition proposals in the half-billion-dollar range from national insurers that wanted unfettered access to UPMC's hospitals. The insurance company now is an even more attractive, more valuable asset. So would the health system consider an offer to sell, spin off or merge its commercial health plan with another company's as it did back then -- before ultimately deciding to go it alone? UPMC says no, it doesn't plan big changes to how its for-profit subsidiary is operated, although it wants to continue expanding its insurance services division. That means picking up more Medicaid and Medicare policyholders, more vision and dental customers, more workplace and behavioral clients -- and more market share for its commercial products. But even as the health system's spokesman blames talk that it might sell on rival insurer Highmark Inc., some insurance industry pros say the timing could be right for a course change for UPMC -- either going for broke and trying to topple Highmark from its perch or shedding the commercial, under-65 health plan by selling it to a national operator.