They should give Shane a twin brother that he never knew about
I think they should press on with the Governor. At least for the first half of S4. It's too good a character and actor for the show to dismiss.
Not really a fan of dragging out the Governor and the prison arcs over to S4, but perhaps we could follow two separate groups? In the comics Rick and Carl escaped the attacked prison and met up with Eugene, Abraham etc so maybe we could follow that group getting to the Alexandria Safe Zone whilst the rest of the group (Daryl, Merle, Glenn etc etc) fight the Hunters, giving it potentially two villains.
None would survive.