Environment version: 4.0.30319.42000
Json.NET version: Newtonsoft.Json, Version=11.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed

Output List<KeyIdObject>: 
[
  {
    "key": "Soccer",
    "T_id": 0,
    "Children": [
      {
        "key": "ClubA",
        "T_id": 1
      },
      {
        "key": "ClubB",
        "T_id": 2
      },
      {
        "key": "SubA",
        "T_id": 3,
        "Children": [
          {
            "key": "SubE",
            "T_id": 3
          }
        ]
      },
      {
        "key": "SubK",
        "T_id": 3
      }
    ]
  }
]

Input JSON: 
{
   "Soccer":{
      "T_id":0,
      "T_state":"valid",
      "Clubs":{
         "ClubA":{
            "T_id":"1",
            "T_state":"Champs"
         },
         "ClubB":{
            "T_id":"2",
            "T_state":"Runnerups"
         }
      },
      "Subs":{
         "SubA":{
            "T_id":"3",
            "T_state":"Unfit",
            //this is nested key
            "SubE":{
               "T_id":"3",
               "T_state":"Unfit"
            }
         }
      },
      "Subs_Used":{
         "SubK":{
            "T_id":"3",
            "T_state":"Unfit"
         }
      }
      //many more nested n-levels   
   }
}