When new binary beta will be available for download ?
There is no set date for an official beta right now, some things still need to be ironed out. You can see a list of issues related to 3.0 here.
Additionally, while these are not official builds, you can download daily builds of the latest Godot 3.0 developments here: https://bintray.com/calinou/godot/editor/_latestVersion#files
(This is a permalink that always points to the latest build available, feel free to copy it and bookmark it.)
You are right , it's a long way to Beta phase.
Think of Godot 3 like Arch Linux, it's a rolling release at this point..
great...thinking of engines as constantly updating <.<