Just one example of the continuing use of Keybase: the Chia Network uses Keybase Chat as its sole official communication tool for its community. More than 20,000 members and hundreds of messages per day. Why Keybase and not Telegram? Because identities can not be faked on Keybase. Private messaging on Telegram (and on Discord) is full of scams because of faked identities.
Another example of possible use: the Keybase File System, for private or public sharing of files.