Based on the last new Fiat's i would not be surprised to see a bigger change to the new Panda then just a few design upgrades.
If it, in fact will be Mobi based, it will change completely with a lot of Mobi design in it to keep the cost down.
So it will have a Mobi body with all the bold-on parts making the only difference between them.
Doors, fenders, hood, bumpers and lights would be different compare to the Moby.
Personally i don't expect that i would like the new Panda, but i hope Fiat will surprise me with the new one.