Is there an avenue to extract from SACD?
Yes. Certain models of Sony's PS3 can be jailbroken and allow ripping of SACD ISOs, which can then be converted to DSF or DFF. It is not a difficult process to load the software on the PS3; more difficult to actually locate the correct model of PS3 which supports SACD playack AND is still running an older firmware that allows the ripping software to be loaded.
In the last 6 months I've ripped ~300 SACDs successfully using the process and cannot tell any audible difference during comparisons between the rips and multiple DSD albums I purchased from Acoustic Sounds prior to obtaining the Playstation solution.
As you mentioned, this is unfortunately the only way to obtain DSD files of some albums that have not been released for sale as downloads and I've found it very useful with some fantastic sounding SACDs from Mobile Fidelity and some Japanese SHM SACDs.