While groups such as the Maltipoo Club of America are actively pursuing the possibility of having this breed be accepted into the AKC as a new, purebred dog, in order to have this happen one of the 1st steps is to have a solid standard for the dog.
As of now, too many people are breeding in different ways and this causes the puppies to vary quite a bit. Right now, there is too much of a range in regard to weight, height, body structure and so forth.
To promote this "hybrid" breed, those who are fond of the Maltipoo and do want this dog to eventually be accepted as its own breed and not a "designer dog", "hybrid" or mix encourage only 1st generation dogs.
It will still take many generations, however eventually if enough breeders hone in on certain attributes of Maltipoos, they will have a completely distinct appearance.
Right now, some will tend to look more like Poodles and others will lean toward the Maltese appearance. However, with good breeding practices, in the foreseeable future the Maltipoo can emerge as its own recognized breed.