Right, and that worked SO WELL in Canada and Australia! Having to make reparations to abused kids, destroying the culture and not really replacing it with anything...
One of the more shameful episodes in our past, I must say.
But we're not talking respect for culture, reparations, or shame here. We're talking autocracy. As was said before, there was very little regard for the non-Semitic speaking, non-Orthodox populations. Thusly the best attitude would be a "white man's burden", where the whites are the Ethiosemitic Amhara, Gurage, Tigrinya, and other groups, perhaps Christianized Oromo. The remainder are to be converted and their identities erased and replaced with a generic "Habesha/Ethiosemitic" one. Completely unkind, but a possible way to counter ethnic heterogeneity. "Meiji-Ethiopia" would not be liberal-democratic, at least not for the Ethiosemites, nor was Japan, unless you want to tell me liberal-democracy spawned the Greater East Asian Co-Prosperity Sphere.
The idea would be to instill a sense of "Amharic" culture, an injera-eating, tej-drinking, ekista-dancing culture for those completely alien, and an Amharic-speaking, Ethiopian Orthodox mentality for those not so unfamiliar (i.e., Oromos). Following that, intermarriage might be encouraged as to make them less Ethiopanised aliens than part of the nation. By the time ethnic nationalism comes around, no one will be able to tell who is what, or who they are themselves, except the non-Amharic Ethiosemites. You'd get a Sneetches-like situation, where the elite group cannot tell themselves apart from those who followed their image.
The whole process would be very, very ugly, but in the end it would work, and there would be virtually nothing you could do about it, as everyone would be trying to be the majority rather than the minority.
As for essential natural resources, you have to realize that very, very, few of the possible natural resources in Ethiopia have been discovered. Real exploration has only started within the last decade. A recent study showed that there could possibly be 300 Mt. of coal reserves in the country. In the mid nineties, 140 million tonnes of potash were discovered in what was Welega Province (wikipedia states that,"
Since the 14th century, potash was widely produced by Ethiopia. It was their number one export up until the 20th century; however after the Ethiopian War against Kenya it became irrelevant." There's never been an Ethio-Kenyan war, so the veracity of that statement is dubious). If it could be found, Ethiopia would have the coal necessary for industrialisation, and could export gold and potash, as well as salts and other minerals.