im sorry guys,im a bit young to remember the old regulations with ground effect, could some one please explain what it does? 
Basically put it manipulates pressures of air travelling underneath the car to 'suck' the car onto the track.
ah thank you for that, with that in mind the red bull will have every pole and race win oh damb lol 

Will this lead to another rather large change in apearance of F1 cars?
Just look at the Brabham from 82 to 83.
1982: Ground Effect F1 design

1983: Ground Effect banned, aero main downforce generator.

For the record though, overtaking in 83 was pretty awesome still.
Bringing ground effect back won't do the trick in my opinion unless they totally ban the extra aero junk on the cars.