Large-scale DLC-esque mods like this don't tend to ever give out release dates, even tentative ones. It can be easy to want to have a date to look forward to, but these things operate on a often very variable time schedule. I know really nothing about The Frontier or the team behind it, but I know a little about these projects and how they work. They can make really great progress, look like they'll be done in a month, and then the next week make hardly any at all. It all depends on the team, they are doing it for free, after all, and have life to focus on. Not to mention the fact that a really important person could suddenly drop out of the project one day and it would change everything. So they likely don't give dates out just for that reason.