ADBC is a deprecated technology. XFA forms have been able to use OLEDB since at least XFA 2.4 (current spec is XFA 2.6). Adobe has made a decision to push their dynamic XFA-based forms as the future of electronic forms since they see it as the better technology that has more potential to provide sustainable profitability.
I have heard nothing about removing ADBC functionality from future releases. OLEDB is a more standardized data exchange format and is the future of XFA forms, simple as that.
I miss my VIC-20, but you don't see me whining about why Commodore isn't still making them.