Q:
masteries outside HoT?
A:
There will be masteries in core Tyria. Also you can only train those masteries while in core Tyria (and can only train the Maguma masteries, such as gliding while in the new maps), you also can not use the Maguma masteries in core Tyria.
The other line besides precursor collections being added (that they’ve announced so far) is for fractals, but no info on it other than the tier names.
There will be mastery points that you can earn in the core world though, and you can spend them on either the new maps masteries or the core world masteries.
Edit: And just to provide some more info, you must own HoT to use any of the masteries in core Tyria.
there are separate masteries for use in old world , precursor collections being the main one ( i believe they previewed one other don’t remember what it was though)