I wouldn't really expect any word on anything Smash related until around April at this point. We were told it'll be awhile and the first fighter's pass is out now, so its time to just sit back, relax, and enjoy what we've got for now. I'm guessing April or May for some kind of Tease as they're likely buckling down to release 2 more this year and the final 4 next year.
Just for fun, I'm going to try and predict the Drop dates for the second pass:
April/May Tease or Reveal
June - DLC Fighter 6
September Trailer Reveal
October - DLC Fighter 7
Early January Trailer Reveal
January - DLC Fighter 8
April Trailer Reveal
May - DLC Fighter 9
August Trailer Reveal
September - DLC Fighter 10
Late November Trailer/Teaser
December - DLC Fighter 11 (Final Character released on 3rd Anniversary for Smash Bros Ultimate)