Is it permissible to pray Asr with the Wudu of Dhuhr if the one performing Wudu intended to pray only Dhuhr with that Wudu, but then changed his mind and wished to pray Asr with the Wudu of Dhuhr? Is this a matter of scholarly disagreement, and what is the preponderant opinion?

The disagreement concerns the issue of someone who intended a specific prayer and no other: their minor ritual impurity is removed, and they are permitted to pray as much as they wish with that ablution. This is the correct view according to the Maliki, Shafi'i, and Hanbali schools. As for the Hanafis, they do not stipulate intention for the validity of purification at all. The conclusion is that purification is valid absolutely, and whoever performs ablution with the intention of being permitted to perform a specific prayer, excluding others, may pray as much as they wish with that ablution.