If Christina of Sweden was successful in gaining the throne of Naples for herself in 1657 (no Monaldeschi murder), how would European history be affected with a Swedish dynasty ruling Naples, possibly for decades?
I say decades because I think that Spain would try to get rid of Christina or her successor, or that the Italians of Naples wouldn't like being ruled by a Swedish-Lutheran-born queen, and try to overthrow her and replace her with a French monarch, which is what was favored by the Neapolitans at the time.