WONDER WHAT the health care environment might be like in the new millennium? You might be interested in some of the predictions in a new report developed by the American Hospital Association's Society for Healthcare Strategy and Market Development and its Division of Trustee and Community Leadership. The report, Beyond 2000: HealthTrends in the New Millennium, says that, by 2002:

* Enrollment in health maintenance organizations will surge to 100 million, or 40 percent of the population, and Medicare HMO enrollment could swell to 25 percent of seniors.

* Hospital inpatient days will drop by another 15 to 25 percent as patients are shifted to lower-cost services and settings.

* Inflation will return as health care spending rises to as much as 17 percent of the nation's Gross Domestic Product.

How did the AHA reach such conclusions? Some 364 hospital leaders-physicians, hospital trustees, chief executive officers and other health care executives-were asked to gaze into their crystal balls and predict the future of health care.