How do non-JRI "$"-prefixed JSON Schema keywords relate to JRI?

[handrews]

Setting aside the special case of $comment (see #9), should JRI reserve the current $-prefixed JSON Schema keywords so that extensions do not redefine them? What about possible future $-prefixed keywords?

My general sense is that things like $schema and $vocabulary are unlikely to be used by JRI extensions anyway, and certainly not by any that expect to be usable with JSON Schema, so there's not much need to explicitly manage the namespace, but I'd be interested in any alternate views.

Note that some form of $dynamicAnchor and $dynamicRef could end up being JRI extensions (usable outside of JSON Schema) rather than part of JSON Schema, so there's not a clear distinction between current JSON Schema keywords and possible JRI extension keywords.