Access parent or root data in nested expression

[Stadly]

For example, how can I extract all the people having age larger than minAge?

{
  "minAge": 20,
  "people": [
    {
      "age": 20,
      "other": "foo",
      "name": "Bob"
    },
    {
      "age": 25,
      "other": "bar",
      "name": "Fred"
    },
    {
      "age": 30,
      "other": "baz",
      "name": "George"
    }
  ]
}

I'm imagining something like this:

• people[?age > {minAge}], where {...} is an expression that is evaluated using the full JSON document as data, instead of the current node.
• people[?age > @..minAge], where @.. refers to data one level above the current node. @... would refer to data two levels above the current node, etc.
• people[?age > $.minAge], where $ refers to the root data, just like @ refers to the data of the current node.

Is something like this possible, or are there other ways to achieve this?

[springcomp]

For the record, we have submitted the $ - root-node reference proposal.