Honestly it doesn't really sound like new information. Just a new way of referencing the same thing. They've said for years that back sleeping helps reduce the risk. The majority of "SIDS" deaths are related to "unsafe" sleep environments... but there ARE still some that there is no explainable reason---nothing in the crib, the baby on it's back, etc. MOST, however, seem to be related to accidental suffocation (blankets, on their tummy, rolled on by cosleeping parent, trapped between pillows/cushions, etc.
Really, it just sounds like PR to try to change the name so that people will associate it with the fact that back sleeping alone really does impact the percentage of babies who are likely to die suddenly for "no reason"--which really just means that it is a step that reduces the risk of accidental suffocation. They haven't "discovered" the "cause" of SIDS. What they have discovered, is that a lot of the reporting of SIDS is misreported and often it is more of an accidental suffocation situation than purely the baby stopped breathing for no known reason. All SIDS means is that they don't know what happened.
They want to change the label b/c they think that they are getting a better grasp on what might be happening in a lot of cases: accidental suffocation.
At least that is how I read that article.