“One thing hasn’t changed however: anybody who publishes data can make their datasets discoverable in Dataset Search by using an open standard (schema.org) to describe the properties of their dataset on their own web page.”
“If you have a dataset on your site and you describe it using schema.org, an open standard, others can find it in Dataset Search. If you know that a dataset exists, but you can’t find it in Dataset Search, ask the provider to add the schema.org descriptions and others will be able to learn about their dataset as well.”
By reading these two parts (excerpts) of the text, I understood that Google is not interested in using other standards at the moment.