(so marvelous or horrible that it may be) the first and probably the last 意味

• (so marvelous or horrible that it may be) the first and probably the last
  空前絶後
  くうぜんぜつご
  

• first and probably the last:    空前絶後の
• probably so:    probably so確かそうだたしかそうだ
• that may be so:    そうなんですけどねぇ