Curious to hear your plan!
My daughter is sensitive to dairy so we're avoiding cow's milk altogether. She seems fine with cheese/yogurt so she gets some calcium that way and we'll supplement the rest and other necessaries (fat, protein) through solids.
That's all I've got. I haven't thought through another logistics yet.
Re: Anyone else planning to give Almond/Coconut milk instead?
Don't worry if your child has already had rice drinks. There's no immediate risk to them, and there are unlikely to be any long-term harmful effects. But to avoid the possibility of them taking in any more arsenic, it's best to switch to a different kind of milk.