Are you referring to the C16 which was from back in 2016, or have you heard about something new ?
The way I understand it, Titleist has established a two year development/release program for their clubs. They alternate year by year with releases of irons and hybrids one year followed up by drivers and fairway woods the next. Given Titleist has just released the new TS models for 2019 I would not expect a new version for a while. Are you saying you have heard about the 2021 prototype already ?

If you mean the one shown at the PGA Show last month, just what a couple of people wrote about it.