Hmmmm...I suspect we'll see something eventually.  In the meantime, if I were to run a mass combat, I'd probably model it on the Action Sequence.  But beyond that structure, I'd do things a bit differently.

First of all, instead of brute squads, I would just have a wound count the players had to buy off each round, depending on where they were in the field.  Then they could use the rest of their raises to move about the battlefield or employ tactics and focus on events.  Knowing myself the way I do, I'd either put together two tables or card decks, one labeled Hazards and the other labeled Opportunities (maybe something more original).  Each round, I would flip a Hazard card for something big and nasty to happen.  The players could spend raises to thwart it.  If a player has any raises left over, they could spend one to draw an Opportunity, which would play out like Events in 1st edition.  These Opportunities might trigger an Action or Dramatic Sequence within the larger conflict.  Yes, I'm a convoluted guy which is why I don't design these games for a living.

As to who wins and loses the battle, I might put that to the players, sort of like "I fail."  Maybe victory costs everyone 1 raise off the top each round.  Maybe failure nets them a HP and something cool.  But ultimately, I would want the game to focus on the little exchanges on the battlefield.

There's a rough draft for you.

FYI, here's a list of the "heroic" opportunities from the GMG and Montaigne books so people understand what I'm talking about here.

• Medic
• Pick Up the Banner
• “Hold This Ground!”
• Break the Line
• A Clear Shot
• Draw the Line
• Save a Wounded Comrade
• Take the Enemy Banner
• Duel 
• "Charge their lines!"
• Cavalry Unhorsed
• Firing Commander Falls
• "Take this message..."
• Wounded Porte Mage

I had thought that Mass Combat could be run like a Dramatic Sequence. I tried to discuss this idea with Mike Curry but he exhibited some strange intransigence with regards to entertaining the idea of Mass Combat mechanics. 

My idea was that because there are too many troops on the battlfield, it makes sense to treat groups of troops like Consequences and Opprotunities in a narrative Dramatic Sequence. 

An example "Dramatic War Sequence" could be to safely escort the Queen across a hostile battlefield. 

The Players start this Narrative with a number of Raises between their group of Heroes and heroic "Brute Squads" (the run-of-mill mooks).

Because this is Mass Combat, Risks are automatically involved. Risks may cause wounds to the Heroes or wipe out a group of heroic mooks.
In response, Players spend their Raises to mitigagte the adverse effects from such rRsks. Players may also take advantage of Opportunities on the battlefield by narrating interesting and heroic actions to convince the GM to alter the sequene to the heroe's advantaege. 

For example, one Hero may spend a Raise to rally the heroic mooks back into the fight. Another Hero may spend a Raise to cause a distraction. This allows a third Hero to sneak past the first enemy group. The remainin heroes may spend another Raise to "hold the line" to buy even more time by engaging any enemy Brute Squads still trying to target the vulnerable Queen.

You could move whole combat units using this simple mechanic of Raises for a major movement action such as charge the enemy, volley fire, rally troops, etc. 

A Dramatic Sequence offers a quick resoluton by setting a timed end to the secne (total Raises) like a chess game with 8 or more moves to checkmate.