[DeltaMasterMind]

All this speculation, oh my! From what I read on the Paizo forums it is anyone's guess since they want to make some changes based on what the playtests show as working better than the original model (1.0). The main changes will most likely come from the way we do action economy and other rules. Stat blocks will remain mostly intact and that is from the mouths of the creators themselves. So monster manuals are safe, for the most part. The core rulebook will be where the biggest changes come from in the form of game mechanic changes. Basically I see alot of D&D 5th rules being implemented, but with Pathfinder flavor (i.e. Touch ac and the like).

As for LW's ability to convert the Pathfinder stuff from 1.0 to 2.0 may be a bit tricky if they do change the action economy, but let's be real here just like all the other game systems there will be options for Pathfinder 1.0 and 2.0 just like there are for D&D, Shadowrun, etc etc. The best part I can say for certain is the conversion of material updated to Pathfinder 1.0 will be easy to update to Pathfinder 2.0.
I remember the creators saying that the action economy in their eyes will be "easier, yet still have 3 parts" similar to Standard Move and Swift actions. Hell it may just require a simple renaming update to all the packages and boom you are running 2.0!