These are the things the Character Ref team are currently thinking about changing/adding to the rules. None are yet set in stone and more details will come out closer to the time.
Look at shield costs at higher levels
Rework pain effect from Wrack to be consistent with Thunderclap
Define Stunned as an effect for above.
Rework Temple of Life and roleplay/theme of Life following Healer split
Move Armour Standards into the core rules.
Fix Half-Elf Staff costs for Warriors, Priests and Scouts.
New amazon draft
Revisit traps, looking at moving Trigger Trap and Hold trap to scout abilities, and some instant traps to make more usable as a player. Also rebalance Aura of Trap Immunity.
Reword wording around Path of Nature to remove unintended miracle stacking
Healers
Add to game
Regrow
Rework regrow missing limb option.
Reattach
Balance against regrow. Somehow. Add to rules as freely accessible casting.
Background Skills
Add more examples to how to apply background skills
Codify manufacturing skills and times for mundane items
Codify costs and times around Masterwork Equipment.
Armour abilities
Add in some form.
Items
Add Rapid Attunement as an item option
Add examples for resolving Bound and Attaching items.
Monster Manual
Rework Monster Manual. Add broad categories with descriptions and consistent immunities/vulnerabilities.
Revise/Define phys-rep standards for armour.