from what I read most of the core members died. Saitou was the only one who really lived to a ripe old age and was successful.
Yamanami san gets assasinated by Okita after he tried to run away (Hijikata's Orders), Kondou San and Hijikata San both KIA. Don't know what happend to Sano or Shinpachai:/ I haven't read anything about the Ichimura bros. or Susumu so I guess they are fictitious. Course my info is the net and mostly seems fan sites so who knows:/
Its pretty sad story though either way you look at it[img]i/expressions/face-icon-small-sad.gif[/img]