That google users can only communicate with other google users in the near future, whereas they can now communicate with every other jabber-user on other networks and services. For example, I run my own server on my own domain, and up till now it was perfectly possible to communicate with GTalk-users.

To paint the picture: it's like when from now on you can only send and receive e-mail from other GMail-users with your GMail-account. You cannot send e-mail to @outlook.com or any other e-mail service anymore.

Also note that XMPP is an open and free protocol allowing for cross-service communication, very akin to e-mail. Google, Facebook, Apple and Whatsapp all use this protocol, but don't allow cross-service communication.

Google is really going down-hill lately. The "Don't do evil"-label has been dropped long time ago, and now their services are just as vendor-locked as microsoft's, facebook's, twitter's etc.

I stay very clear of google. Not only for privacy reasons, but also for the continuity of their services.

As for XMPP, there a lot of free services available which DO support federation. jabber.org, duckduckgo.com to name two.