As you can see, the starting is a bit slowly but increased the speed over the process. If you are an extension/template developer, you should reserve some time at the beginning of March 2017 to test your extensions/templates.
3 Big Features Included in Joomla! 3.7
- Routing: A new routing will be applied in Joomla! 3.7. It will be an option and you can enable it per component, so you can mix the old and new strategy. If you are using an old extension that does not support the new routing then everything will still work as before.
- Custom fields: It is now merged into the staging branch that’s the branch of Joomla! normally used for development.
- Associations Manager: It is a Google Summer of Code project that is planned to merge soon.
That are not all in Joomla 3.7. There are many other improvements in Joomla! 3.7 that you will surely be interested in.
You can follow the development stage on Github and if you have time to test a feature please do it. The more people testing the better will be the quality of 3.7.0 on release day.