Existing would certainly be grandfathered, I'm sure. Under the proposal, sprinklers would be required for distilled spirit storage quantities over the Class 1C flammable liquid MAQ, up to 10 feet in height, 2 racks (flu space) with 3 barrels per row in each rack, or single rack with 4 barrels per row.
Here's the link to the full proposal (search for F127 – 13): http://www.iccsafe.org/wp-content/uploads/00-CompleteGroupB-MonographUpdates.pdf