The change that could prompt their return is the move to lower and wider rear wings. Last year the wing was 950mm high and 750mm wide. This season the respective figures are 800mm and 950mm. It means that on most cars the rear wing will suffer more from the turbulence generated by air coming off the front axle and suspension.
The shark fin solution, or airbox sail as it is sometimes described, dates back to 2008 when Red Bull introduced it on their RB4 machine (pictured above). It helps to divert turbulent air away from the rear wing, especially while cornering.
Ironically, Red Bull are one team who may be less likely to go down this route for 2017. Running a high rake angle on your car - as the former champions are renowned for doing - actually lessens the effect of the turbulence coming from the front, as more of that airflow simply passes under the rear wing.
https://www.formula1.com/en/latest/technical/2017/1/tech-insight-shark-fins-set-for-2017-return.html