Very interesting stuff, definitely a good decision overall imo.
Some questions though, mainly with how getting the replacements will look like for players.
1) Let's say I have two copies of the Sun Reaver card, one of each affinity. After the changes, will I have two copies of the new Sun Reaver instead?
2) Let's say I have a Cluster Explosion (P) \ I don't have a Cluster Explosion (P). Does it make sense for me to hold on to it \ buy one now off of AH to get a better replacement after the patch?
3) Let's say I have a two copies of Time Vortex of each affinity up on the AH when the patch hits. Will the cards be automatically de-listed and given to me back in their new version?
There may be other things I'm not thinking of right now, but overall the main question is: how will it look like for the player? An automatic replacement? Or will it be a trade-in type of situation? This may be a technical challenge for you guys.