Proposed changes will not modify existing characters themselves. That means no new feats/abilities per class will be initially lost or gained. However, if a feat/ability is modified in some way though (as in it exists on the character's character sheet), that will affect all characters. So for example, if someone is already a level 8 assassin, they won't just login one day and the the HiPS feat will automatically appear. Instead, it is my intention (and keep in mind this is ALL in 'rough draft form' at this time) to setup a brand new class checking/correcting section of code in the game's "OnLevelUp" event. That code will ensure that immediately after a PC levels-up, they are properly modified/setup for their class(es) modifications from standard NWN implementation. This will also be needed, in part, because the level-up summary for PCs -especially those who take modified PrC classes- may no longer be entirely accurate as far as speciali abilities gained.
So in other words; every time a PC levels up, it will cycle though what classes a PC has and remove, or add, feats/abilities/spells that can be cast/etc that differ in Thay from the way NWN originally implemented the class.
As far as changes to factions-becoming-classes, that I have not really thought through as -while I would like to implement things like the Red Wizards and Thayan knight PrCs- right now I just don't know. I want to avoid/eliminate relying on DMs to help re-level PCs in those factions. Most likely they'll just remain in whatever classes they are, with the benefit of being able to take the new PrC level son their next level-up. But I've also got over 100 spells on the to-do list as well. Between that and just the modification to the existing classes, I have more than enough to keep me busy for...well...possibly months.
So in other words; every time a PC levels up, it will cycle though what classes a PC has and remove, or add, feats/abilities/spells that can be cast/etc that differ in Thay from the way NWN originally implemented the class.
As far as changes to factions-becoming-classes, that I have not really thought through as -while I would like to implement things like the Red Wizards and Thayan knight PrCs- right now I just don't know. I want to avoid/eliminate relying on DMs to help re-level PCs in those factions. Most likely they'll just remain in whatever classes they are, with the benefit of being able to take the new PrC level son their next level-up. But I've also got over 100 spells on the to-do list as well. Between that and just the modification to the existing classes, I have more than enough to keep me busy for...well...possibly months.