Honestly, I could very easily see a two-deck system setup like GoT, with a main deck involving Personalities, Holdings, Attachments, and Strategies (or whatever you want to call them), and the other having "Provinces", or contested areas of Rokugan your Clan is trying to gain control of, with some sort of way to determine whoever gets X Provinces or Provinces with X value first being the winner. I could see Personalities with four stats - Force (military strength), Chi (spiritual strength), Honor, and Glory (political strength) and probably no loaded keywords (you can handle most of those effects through an ability on the card), just basic stuff like Samurai (I know they are all samurai but honestly just for marketing if you have a samurai game you want to have cards on them that say samurai), Courtier, Shugenja, Shadowlands, Unique, and maybe some really flavorful ones like Ninja, Monk, Daimyo, or Ronin purely for card interaction purposes. Perhaps the aforementioned Provinces have 3 sets of 'Province strength', Military, Spiritual, and Political, all with different values, and you try to contest those Provinces and claim them by attacking one of those types of values with your people, representing how your Clan tries to gain control of the area and its populace. There could even be a mechanic for each of the Five Rings not unlike the Small Council, where you choose one of the Elemental Paths and try to achieve something in order to 'gain enlightenment' in that path, and you win an "enlightenment" victory bu achieving all five Ring Paths during the course of a game. Just a quick couple of thoughts, with plenty of room to flesh out and develop, but I could see a basic framework with something like that in there.

There were many design aspects that couldn't be let go because it would have essentially invalidated every L5R card made up to that point, and we always tried to take into consideration that fact when deciding on any significant development changes. FFG has stated they don't intend for their game to be mechanically compatible to Classic L5R in any way, so there are lots of things I am sure they will now have more freedom to address.

I wouldn't be surprised to see Samurai, Ronin, Ninja, Courtier, Monk, Shadowlands, and Shugenja possibly be the only keywords retained (as well as Unique and possibly Daimyo).

This is pretty much the best advice you can get at this moment on this subject.

Finally, I can be my corrupted self! I assume art-specific avatars will depend largely on what art assets FFG picks up in the transition, and what they may have to re-negotiate. Since the helmet and sword art for the announcement of the accquisition of L5R was from a card from a set that may never be released, I can assume they picked up some art assets set for Onyx Edition and beyond.