Some additional rationale which is not part of the TIP:
To make it easier for Oracle users we could provide a mailing-list or RSS feed where we publish all changes to acs-core "-postgres.xql" files, so they can figure out if somthing needs to be done.
If the .LRN consortium wants to continue providing Oracle releases than the responsibility is just lifted from the OpenACS community onto the .LRN community, no change will happen for the Oracle Users at large.