Do your molars shift sideways after wisdom teeth removal?

Not usually: They will usually assume a position based on the opposing teeth in the opposite arch. If they were trying to go there and the wisdom teeth prevented it, then they might, but not common.

Not likely: Teeth move when the forces that play on them are not in equilibrium. The muscles in your mouth tend to push teeth forward, so it is very unlikely that the removal of the last teeth in the arch will cause spaces to open.