If he beats PBF, People will let the Pac fight's slide... (EXSP: After Cotto get's in Pac) Considering most people already gave JMM the win/wins over Pac. (Mind's eye style) Top 10 MEX fighter of all-time... #1 no, Maybe top 6....maybe (Depends on how much people truly value PBF)
Maybe top 6 Mexican?? Can you really name 5 fighters that have that level of resume (adding on the PBF and Pac victories)?
If he beats Mayweather and then Pacquiao, imo Marquez should be ahead of Chavez as the greatest mexican fighter of all times.