Ono stated that he would like to make a Nintendo X Capcom game.
Developers for Marvel Vs. Capcom 3 had wanted to put a number of cameos from Breath of Fire in the game (Fou-lu from Breath of Fire IV was specifically mentioned) but this was eventually nixed as the Breath of Fire series was seen as "too Japanese for a game aimed at Americans".
The planned appearances did eventually happen in the form of power-up cards for the "Heroes and Heralds" mode of Ultimate Marvel Vs. Capcom 3, but to date Breath of Fire is one of two known Capcom series (the other being Power Stone) that have never made a full appearance in a "fighting" Capcom vs. Whatever.