Honestly, this would not have much of an effect. Lechfeld was the end in any case. The Magyar raids had been dying down for years beforehand. This battle was merely the final nail in the coffin. By 950, the Magyars did not threaten Germany anymore, and indeed the Ottonians were on the offensive against them. Otto dying, leaving either no son or a postmortem Otto II would make things very interesting. I could see the aging Henry I of Bavaria (Otto's brother) and his son Henry II claiming the throne (or at least a regency) based on proximity of blood. There would probably be revolts in the Marca Geronis (Slavic marches beyond the Elbe) against German rule, and ditto for Lusatia.
Interestingly, Saxony, Swabia, Lotharingia, and Bavaria were all controlled by the Ottonian family (or relatives thereof) at the time. Otto the Great ruled in Saxony (with his subordinate Hermann wielding de facto power in 955), Otto's son Liudolf ruled Swabia, his brother Bruno was the Duke of Lotharingia, and Henry I of course ruled Bavaria.
Hermann, Liudolf, Bruno, and Henry I (and Henry II) all are candidates for the throne. I could definitely see a civil war between the four, each using their respective duchies as bases of power to draw men from. This would strengthen the independence of each duchy, leading to the victor ruling over a weakened Germany facing a crisis in its eastern marches and revolts throughout its homeland.
Sounds like a good TL.