From the Mihon Discord, which is fork of Tachi:

Yes, Tachiyomi has announced that it will cease development

Q: What can you do?
A: You can continue to use Tachiyomi as always until future Android updates may break the app. There will be a Mihon release soon tm. No ETA.

**Q: What is a fork? **
A: A project fork happens when developers take a copy of source code (Tachiyomi) and start independent development on it

Q: What is Mihon?
A: Mihon is the spiritual successor of Tachiyomi, picking up where it left off. There will be minimal differences between the two to ensure ease of migration, such as backups, restores, and look and feel. Currently, there is no official app yet. There will be a Mihon release soon tm. No ETA.

Q: What will happen to TachiyomiSY?
A: TachiSY will still be around, and will continue to act as a fork, but off of Mihon instead of Tachiyomi. No ETA

Q: Should I stick to TachiyomiJ2K?
A: J2K is currently outdated and not recommended to use as a fork for now. You'll have to wait for an update. No ETA

Q: Should I stick to TachiyomiAZ?
A: TachiAZ will still be around, and will continue to act as a fork, but off of Mihon instead of Tachiyomi. No ETA

Q: Should I stick to Neko?
A: Neko will still be around, and will continue to act as a fork. However, it won't be forked off of Mihon.

Q: Will Mihon be safe from Kakao?
A: As of right now, AntsyLich has stated that Mihon will be safe from legal repercussions as long as there are no built-in extensions repos in Mihon or the forks. In other words you'll need to add your own or a 3rd party repo to the app in order to read, just like Tachiyomi did. It didn't prevent the core team from leaving. We strongly encourage all users to exercise caution, and avoid utilizing extensions from unknown repositories, as they may contain malware.
All future apps/forks will implement this to prevent legal repercussions. We will implement more countermeasures and will think of more ways to protect the new core team from companies like Kakao Entertainment as we're working towards the new releases.

Use Dantotsu. Right now it's broken because it uses Tachi's extensions, but they plan on fixing that.

@MentalEdge @Decide what are you using to read manga files in .cbz format, .cb7, pdf, etc., on android?