A report in Tech Times speculates that Samsung will soon provide enhanced annotation tools specifically for PDF documents.
The source does not say if the feature will be proprietary or will utilize ISO 32000 standardized annotation technology. The information comes from a rather expansive patent application for "Write on PDF" (US Serial Number 86678729). Of course, this may also indicate that Samsung has no intention of using the ISO-standardized annotations model at all.
We'll keep an eye on this story. The money quote is the last paragraph:
It is, on the surface, going to be a small change, but for many Galaxy Note users who depend on the screen writing features of their phablets, such as those who largely use their phones for work purposes, Write on PDF, if done right, will be one of those big, little features that are too valuable not to have.