How is global leadership being ceded to either Russia or China? That would only happen if European countries prefer building economic and strategic ties with China over the US. If that happened it would mostly be revealing the true colors of Europe, choosing to side with a dictatorship and system that has killed tens of millions. As for Europe itself, I doubt Europe will be able to lead anything given its economic condition. These changes essentially just force people to resolve this one conflict.

Europe will prepare for a future independent of the US, as they have proven to be an unreliable and fickle ally. This breaks the western blocks global dominance, as it is now no longer aligned, breaking into two (or more) blocks. As a result, the US loses much of their global influence.