Actually, if you think carefully about SMS messages and voice messages, it is obvious that voice message is more convenient than a text message, since voice message only requires recording and sending, while to text messages, it requires typing, which can be heavy work especially when there is a long text to type. It is also heavy work for the recipient to read through the long text.
Therefore, there is a prediction that voice messages will get more popular than text messages in the market. More people would like to use voice messages to communicate since it is a more convenient technology.
However, text messages will not be abandoned, since that you can not record a message all the time. When you are in a situation when talking is not convenient or allowed, it is better to send a text message. Therefore, it is more possible that these two communication methods will be supplemental to each other in the future, and each of them is very important.
Almost all communicating apps can both sending text and voice messages. This has become a standard-setting, and this combination is the best for the users.