Yes, I hit the trifecta on this recipe. I was able to successfully make a pancake without gluten, dairy (in essence, casein) and eggs! It is a vegan, gluten-free pancake.
I have been cooking gluten-free for 5 years. That I have figured out. I like to use my own blend (see the recipe for the link) in place of flour. I have found, through trial and error, that the pancake is better with some xanthan gum. It holds together better.
Substituting the milk is easy. There are many milk substitutes like soy, rice, coconut, hemp, and almond. If you use something sweetened, cut back on the sugar in the recipe. Instead of butter, you can use any fat; vegetable oil, or melted butter substitute, coconut oil, or shortening. For the most part, fat is fat.
Egg substitutes are a bit trickier. I have been using a mixture of flaxseed with water (1 tablespoon ground flaxseed mixed with 3 tablespoons of water) which helps to hold it together. Another egg substitute can be made with 2 tablespoons of water, 1 tablespoon of oil and 2 teaspoons of baking powder. This helps to replicate the rise. I ended up using a combination of these two to substitute the 2 eggs that