Depends on what you mean by swimlanes: if you mean the bpmn meaning, then swimlanes do not offer valuable execution semantics. If you mean jBPM semantics, then yes we might add that in the future - but nothing concrete is planned there.
IMO with swimlanes, I can easily open the process definition and quickly check the task assignments. Yes, it can very will be done using process variables, but then I'm afraid how business analysts would know about the assignments? If not swimlanes, may be support for defining process variables in a declarative fashion could be added (just a thought).