Hard to say.
K-pop is still doing well in Japan even with the current political struggle. The Japanese people have a positive image of JYP. I think in the end it all depends on who the girls are and how much clout the project garners. Iirc they said they would do a tv show so that could help get them a good following. I see their ceiling for first single being Izone numbers. There is no chance they reach AKB or Nogizaka, but something close to what SKE, NMB do is possible if the shows gets a lot of attention.
Right now I think they will sell somewhere between 75k-100k. But a lot will change once more info comes out about who are the prospected members.