Or that his son Valdemar who died in infancy lives.
But going with Christopher and Margrethe still going as OTL that would make for Oluf becoming King of Norway 1380 when his father King Haakon dies.
Also Albrecht of Mecklenburg is King of Sweden while his older brother Duke Heinrich is married to Valdemar's daughter Ingeborg which brought the issue Albrecht (another one).
A few years before he died Valdemar had been able to make peace in the war with the Hansa/Sweden/Mecklenburg/Holstein of 1367-71.
Margrethe might still have Oluf proclaim himself heir to the Swedish throne.
Christopher if he had inherited his fathers diplomatic skills as Margrethe surely had have solved the handover of the Scania fortresses occupied by Hansa since 1370-85.
By internal Swedish conflict Margrethe was asked to intervene against King Albrecht 1386 but this was postponed till 1388 and spawned off a war of 1389-95 where Margrethe emerged victorious. In the meantime Oluf had died 1387 thus Margrethe had adopted the son Erik of her sister Ingeborg's daughter Maria!
Thing is all this may be butterflied away by Christopher being in protracted conflict with the Count of Holstein thus probably not able to divert forces to fight Sweden in allied with Margrethe; he also have to watch the Hansa.
In all the internal Swedish conflict may result in King Albrecht strengthening his power within Sweden thus being able to defeat his opponents and bar Norwegian (Margrethe) intervention. Margrethe may though try to rally diplomatic support.
Albrecht might have been able to spawn off the Mecklenburg Dynasty of Sweden and continue the age old struggle with Denmark though without the Danish supremacy interlude of the Kalmar Union.
So the big picture might see little change in Scandinavia; of course no Danish - Norwegian Union (and the North Atlantic remaining Norwegian) and Sweden might start an earlier expansion east wards having of course conquered Scania beforehand!
