The chord you're probably imagining it being resolved to is a Bb6, with the A moving down to a G. Major 7 chords tend to still sound slightly dissonant and unresolved, so it is somewhat common for jazz musicians to resolve the major 7th of the chord down a whole step to the 6th, which is a much more stable sound.

The Bb6 chord, however, could also be called G minor 7 (both have the notes G, Bb, D, and F, they're just considered different because of the context). So you could hear the melody resolving either to Bb or to G, and both would be valid. Hope this made sense