Some of the SEA-ATL 767 runs with international aircraft have long been great opportunities for even Silvers to sit up front in BusinessElite seating. It makes sense that with the Seattle 767 routes to Asia being some of the longer ones that they'd see the flatbed reconfigurations sooner rather than later.
Interesting they're rotating through JFK, where there's traditionally less demand than ATL - but I certainly won't complain about flatbed seating on a domestic run!