WI: Anglo-Saxons lose the Battle of Brunanburh?

[Kirook]

https://en.m.wikipedia.org/wiki/Battle_of_Brunanburh

In 937, a coalition of Norse, Scottish, Welsh, and Irish petty kingdoms and chiefdoms invaded England to try to keep Æthelstan from unifying it, but were beaten back at the Battle of Brunanburh. What if they had defeated the Anglo-Saxons instead and seized control over more of England?

 

[Kerney]

I think it depends on how they loose. The West Saxons retreating in good order is one thing. Killing the king and his half brother and heir and utterly destroying the West Saxons army is another.

In the latter case the kingdoms are probably United by marriage rather than conquest many years in the future. Former, they try again in 5-10 years.