There was original the idea to use those for a board revision (e.g. A/B) but I have been informed that there are at the moment no plans to use those pins in the software builds. [...] Certainly the current (B-boards only) builds do not use those pins.
Thank you for the very interesting details. From the picture, it seems like there is about 0.05" (1.27mm) room between those resistors, it's relatively easy to solder.
The four pins look like configuration inputs to me, and I guess a driver is needed to activate the I2S on them. But why put the resistors if the config bits are not read? (some are at +3V3, some at GND, here)