Both my sons are allergic to cows milk and so have only had breastmilk for 2 and 4 years respectively. They do like soya yoghurts and ice cream, but won't touch soya milk. I occasionally use rice milk or oat milk in cooking, but again, they won't drink either of them directly. I think as long as they have a good varied diet generally, the absence of cows milk isn't a huge problem. You can get everything that's in cows milk from other sources.After all, there are plenty of societies where cows milk isn't traditionally part of the diet, and lots of perfectly healthy vegan people around too!