I'm hesitant to put too much hope in this discovery.
I would expect a discovery of this magnitude to be published as a full article in Nature, rather than a Nature Letter. I'm not sure of the difference in the publishing process for the two, but Letters generally come across a bit rushed and are less exhaustive than published articles (citation needed).
The difference between letters and full articles is described here [1]. I don't think that one should view the length of the paper or whether it's published as a Letter or an article as a marker for its scientific importance.
For instance, The paper that Watson & Crick published that described the structure of DNA was only slightly longer than a single page [2].
I'm hesitant to put too much hope in this discovery. I would expect a discovery of this magnitude to be published as a full article in Nature, rather than a Nature Letter. I'm not sure of the difference in the publishing process for the two, but Letters generally come across a bit rushed and are less exhaustive than published articles (citation needed).