There are no specific plans yet for JMX data. An interesting option here could be, that instead of pulling data from http, we could have an http that data can be pushed to instead of pulling. Like this the beat would not have to know all the details on how to fetch the data but it would be pushed by a tool. Not sure if something like that is supported by jolokia? The other option could be to push the data to stdin from which Filebeat is reading.
Also feel free to open a feature request.