When Hellions was announced, there were only 4 X-teams (Excalibur, Maruarders, X-Force, New Mutants). Those 5 still exist, plus we now have X-Factor, SWORD and soon Way of X, CoTA, X-men. 10 X-teams is alot. An 11th is way past the point of overkill
FYI, neither X-Force or Hellions are hitman squads. The two teams and the books that they appear in couldnt be any more different