providing for one's own future prosperity is generally considered a question of wisdom rather than morals. However, given that a person and his future mind moment are merely similar entities connected by a near-continuous transformation, rather than being the same entity, it would seem that there must be a symmetry between the moral implications of a person's treatment of others and of his own future.

Agreed. Caring in a deep and personal way about those future mind moments is nearly universal, but no more rationally compelling than caring about other mind moments. One might say that evolution has been keener to instill empathy for one's own future than for the mind moments of others. When it comes to considerations of rationality, the main difference is that, if you care for your own future but disrespect other people, others can typically retaliate in ways that hurt what you value. Whereas, if you care for other people but disrespect your own future, your future self is utterly powerless.

Calvin and Hobbes had a good line on the powerlessness of the future self, in the time travel series. But I suppose I should abstain from providing a link to material that probably violates copyright. So I'll just mention that at one point, Calvin's past, present, and future selves all argue, and one of them says "Go ahead and hit me - my future self will be the one who hurts."