600 are maybe a lot, but Keychain is not only a Browser extension. It also an App.
I think a lot of User use it on their Phone.
It is the best thing to use everything hive has, without the need to use somewhere your Keys, it works on every site.

Hivesql will not work for free, so some Part of my site hivegadgets.com will not work. I won't be able to pay it.

This could happen to other sites also. Maybe many things we have used will not work soon.