My dd is also not that keen on milk. She still nurses in the morning and night, and will drink probably less than 8 oz of milk in a day. She does really like the drinkable yogurt, which I mix with milk to cut the sugar, and vanilla soymilk which I also mix with milk.
The one issue you might have with using soymilk exclusively (you can mix it with plain soymilk to cut the sugar, too) is the lack of cholesterol. Until 24 months, toddlers need cholesterol in their diets for myelin (which coats the neurons in the brain) development. But, if he's eating lots of cheese and some eggs here and there, it shouldn't be too much of a problem. People who raise their kids vegan (giving them no animal products whatsoever) are often advised to nurse until age 2 or older so that the child gets enough cholesterol in the diet. B12 isn't a problem unless you are raising your baby vegetarian (which I am), as there is plenty of B12 in meat. Eggs and dairy also contain B12, but in smaller amounts.
