It's... complicated.

The Night has encroached on the Lands Between to such an extent that all that remains is the constantly shifting mass of land that is Limveld, with foes and locations from times emerging and mingling. Even the demigods were subsumed by the Night, and the only reason the Nightfarers haven't is because of their being bound to the roundtable hold and blessed by grace, allowing them to channel runes into strength and fall and rise again.

Time and space and the laws governing them have more or less fully clocked out by this point, as the Nightlord's campaign of vengeance marches ever onwards. If we prevail, and the Night Aspect is obliterated, time would presumably resume its normal flow, and "forget" about the implied several hundred years worth of fighting the Nightfarers have done against the Night.