Health insurer UnitedHealthcare says a contract dispute with SUNY Upstate University Hospital could potentially disrupt care for about 20,000 Upstate patients in the Syracuse area. Upstate’s contract with UnitedHealthcare expires Dec. 31. If the insurer and hospital don’t reach a contract agreement by then, Upstate patients enrolled in some UnitedHealthcare plans will be “out of network” beginning Jan. 1.