Inserting tokens into a text field, such as body For many years I've used the excellent token filter module. However, viewing development activity on the module, (Seeking co-maintainers, Maintenance fixes only, and last updates are over a year ago) suggests that this module's future may not so bright. Which, in turn, suggests that there is another or better way of achieving similar functionality? For example, I commonly use token filter to construct the current year for the copyright mark. Other examples include referencing the site email or slogan.

What's the best "future-proof" method for inserting token-like content into text fields?
I think you are looking for Advanced Text Formatter module which allows you to enable token replace on fields you choose. The mantainer says it would have a Drupal 8 version too.