I'm cross posting this from my response on another thread - but am not sure how to just provide the URL. Anyway, here goes:
Just received an email back from Kubota with the official response:
"Thank you for your inquiry to Kubota.
The BX tractors are designed to handle a wide variety of three point mount implements ranging in size and weight. Knowing that, Kubota has been investigating the possibility of offering a backhoe for the BX sometime in the near future. As with all new products, it may take some time for development and testing therefore, I could not indicate with any certainty as to the date of availability of this implement."
It may help with the "investigation" if you send an email to TCriss@kubota.com - (this email address is on their web-site, so it's already public)