Hi, I think it's a personal choice hun. They still need around 300ml of milk or calcium from cheese etc, it's just milk becomes a drink rather than a meal really. Think that continues for a while yet. I believe they can switch from full fat to semi skimmed at around 2yrs old but I'm not really planning to.
We still have a straw cup of milk first thing in the morning and one before bed as DD likes it so much. As long as teeth are brushed before BT after the milk, I think there's no reason to stop it if you're still happy?