Mishkoltz (from Miskolc, Hungary)
Nikolsburg[disambiguation needed ] (from Mikulov/Nikolsburg)
Nope :). Mishkoltz from Petah Tikva and Nikolsburg from Monsey and Boro Park. There never was a Chassidus in Mishkoltz. The Mishkoltzer Rebbe in Petah Tikva, who does great work and is very sincere, may be descended from a pre-war official rov of Mishkoltz, but he is the first Rebbe in his family tree.
The Nikolsburger Rebbes just took the name because they may be descendants of Reb Shmelke. However, there was no Nikolsburger Chassidus any more than there was a Mezhibuzher or Mezritcher Chassidus (those may exist today too for all I know).