Studies have shown that mixed breed dogs tend to be average in size. This puppy has some terrier and they tend to be smaller, so, we can probably assume that it will be smaller than average
"Mother Nature" tends to breed for sturdiness, intelligence, playfulness, ability to co-exist with other pets and people and longevity, so we can expect this puppy to be healthy and sturdy. His long haired coat indicates that he will need weekly brushing and grooming. His loving family intends for him to live indoors, so keeping him clean shouldn't be any concern.
It's difficult to predict final size in a mix; a lot depends on the size and structure of the ancestors of your particular dog. Mixes of small dogs should result in smaller dogs, and mixes of larger dogs should result in larger offspring. Long hair may or my not predispose the dog to long hair. It should be remembered that all "full-bred" dogs were once mixes of other breeds.
We are pleased to welcome this puppy to our practice!