Due to increasing competition from national health insurers, some of the nation's nonprofit Blue Cross Blue Shield organizations may be feeling the pressure to merge or to convert to for-profit status. The conversions could, in turn, pave the way for acquisitions by large insurers such as WellPoint Inc. For large managed-care companies seeking smaller, independent insurers as acquisition targets, the independent Blue Crosses and Blue Shields are the most attractive ones because they have the best operations and the most people covered.