As a data point, my grandparents are deaf, and their use of SMS has pretty much replaced TTY Relay, and made it much easier for them to have quick conversation

As a data point, my grandparents are deaf, and their use of SMS has pretty much replaced TTY Relay, and made it much easier for them to have quick conversation with almost anyone. They still seem to use video chatting within their group of friends with hearing difficulties, but it's reserved for the type of conversations we would have over the phone.