Well, Technically dogs could already have one. They basically understand each other through the actions of the other dog. Such as the action of growling. When one dog growls, the other dog understand it may be threatening or intimidating the other dog.
I'm well qualified to answer this because my dog has been teaching me to speak Canine.
She's taught me to open the front door when she wants to sit on the patio and watch the passers-by. That's different from her wanting me to let her out into the garden so she can find a tree. She tells me when she wants to be fed and what time she wants me to wake in the morning. She can also tell me when to take her for a walk, and when she's walked far enough.
And I won't tell you what she says to me when I take her to the vet or leave her at a boarding kennel.
Yes, dogs have a language of their own but there's nothing unspoken about it.