ENSO still has a fairly…
ENSO still has a fairly strong relationship with US temperature and rain/snow in FMA. Even if La Niña has weakened substantially by then, it can still have some impact. Also, the atmospheric response doesn't necessarily shut off as soon as the SST no longer qualifies as La Niña, so I would think it's likely that La Niña will play a role in the FMA weather. The CPC's outlook for FMA generally reflects La Niña patterns. (These are from September and will be updated on October 20th.)
Regarding the warm subsurface--we are keeping an eye on that! And many climate models seem to be hinting at a warm-up in the Niño-3.4 region for next year. However, this is still pretty far away, so we'll have to wait for spring forecasts to have any real confidence.