It also affirms that Bishop Fellay believes what I have long suspected. Namely that this is probably the best deal the society is likely to get and that Rome is no longer willing to tolerate the status quo. In short Rome is demanding the SSPX return to the fold or face a formal schism. Fellay believes, and I concur, that these are pretty generous terms. Right now the SSPX is sitting out on a limb and it sounds like the three bishops want to saw that limb off the tree.
Read the letter in its entirety at the above link.
(Update 1215 PM 5-11-12)