That is correct, we'll began porting to Unity 5 once its out. There are a lot of benefits that worth the upgrade, not only visual improvements, but major physics upgrades (updating to PhysX 3.3 and reworked clothing simulation), not to mention proper 64-bit editor that won't crash every time it hits any memory limit due to having a lot of assets loaded up within the editor. The more contents you have, the easier it hits the memory limit, the faster it crashes. But I'm also pretty sure the newer lighting engine will give way better results in terms of lighting than Unity 4 ever could.
any idea already of PC requirements?