What makes you think your current vehicle won't need a sway bar? Having the tow package will have no bearing on if you need a sway bar or not. A properly loaded trailer should not sway to start with. Wind and turbulence from other vehicles could still cause it though. A sway bar is cheap insurance to prevent it at all.
Don't confuse a proper trailer sway bar with new vehicle "electronic sway control". They are 2 different things. Vehicle sway control will not stop a trailer from swaying and will only engage after the sway has already started, which is too late.