In what way was Franz Schubert ahead of his time?

He wrote melodies based on the whole-tone scale.
He defied the tonal conventions of the sonata form by combining unrelated keys.
He pioneered the technique of atonal music.
He created the genre of the piano trio.

Franz Schubert was ahead of his time in defying the tonal conventions of the sonata form by combining unrelated keys. This was considered innovative and groundbreaking during his time, as it challenged traditional harmonic structures and paved the way for future composers to explore new tonal possibilities.