Not Islam per se, but a homegrown monotheistic religion with a more contiguous relationship with pagan religions than Christianity had in OTL. How exactly could this reverse happen?
You may want to go on to SHWI and do a search for "Submission"- a fascinating (and rather venerable) TL which explores the consequences of precisely this; the PoD is that the Muslims are defeated at the battle of Uhud and never go on to unify Arabia, while about a century later another Prophet, named Ragnar, appears in Scandanavia...
This post isn't the first one in the series but it gives a good overview.