{
      "name":"Product",
      "properties":{
        "id":{
          "type":"number",
          "description":"Product identifier",
          "required":true
        },
      ...

Though the json representation of json-schema is nicer than XML, I think this approach to a schema language is just as bad as XML Schema. It even looks like they're trying to replicate the features of XS. Which might make sense from an adoption point of view, but ...

There isn't that much difference between hierarchical data formats. Even here, some people favour s-exps or YAML over JSON. So once one gets established it's difficult to dislodge due to standardization, network effects, tools, user familiarity etc. However, it can change when there is a new platform, which starts fresh with a different format.

JSON already owns browser communication (though note the pesky X in AJAX...), since browsers already use JavaScript, but it seems unlikely to usurp XML much further (exception: JS becomes prevalent on the server-side).