Feel if you have a bad throat and hoarse voice, you are not able to speak everything, you do gestures, sometimes you write instead of talking. In the same way we need to give some alternative 2 our children so that they can tell us what they want.
Child may not speak but you can say the name for your child. He is listening everytime and listening helps in recalling. Recalling helps in using it in words. So don’t think ever that communication boards are going to develop a habit of not speaking. I have an experience with apraxia where my student started speaking words verbally once we started using AAC with him. He became a calm and expressive child. Not fully verbal but he was on one word in his first year of AAC who is now on answer questions level with and without pictures.