The specification says the conversation id of non-transient conversations should be automatically propagated, it would however be handy to be able to stop this propagation on a per-component basis. If the request token (e.g. named "nocid") would be present, CDI would interpret this as if no cid was found in the request. This would enable users to jump from non-transient to non-transient conversations in one step (e.g. by using a commandLink with a f:param named nocid and an action that would start a new non-transient conversation.
A further enhancement could be that the parameter value could be "end" and CDI would terminate the propagated non-transient conversation instead of just abandoning it.