Tachiyomi will no longer be actively developed. It may continue to work for you for the foreseeable future but there will be no support for it nor the official extensions.
Hopefully their personal information won't be found out by those lawyers, or they could also be threatened into stopping development. It's sad to see how companies are bullying volunteers into stopping legal projects.
Companies that do that should loose all copyright and patents they ever had in return. I think that would solve the problem pretty quickly. (or the responsible person should get his hands cut off like in the good old days lol)