The Guild Companion has already re-released the original RoCo, and is actively hunting down the relevant authors for the other RoCo titles.
Note that in some cases this may amount to an impossible task - for example: RoCo 2 had more than 14 authors who would have to be found; similarly, although the RMSS MAC only had one author ... he appears to be untraceable at the moment ...
On the other hand, GCP has re-released RMSS Essence Companion, and may be able to work towards some of the other "off-limits" titles with time and effort ...