Oh, a clarification: the Node client will be replaced by the Go version. The `keybase` command line app will be a superset of what's available in the Node client now. Sorry. So yeah - still providing those API's.
PGP support will continue, always, it's just that you won't need to have PGP on all your devices -- just the ones you use PGP on. Your PGP key will be part of a family of keys you're known by. If you install Keybase and have no idea what PGP is we don't make you get a PGP key.
By switching to device-specific keys via apps on every platform, we can solve security and convenience problem at the same time. As the blog post says, this can only work if you can bring pairs of devices together. Which has only been possible and convenient the last couple years.