With a due nod in the direction of political realism; they're going to object outright either way. You've suggested that it'd be a first step on the road to a sensible licencing regime, that's exactly what they're afraid of. They've had a cartel enshrined in legislation and even the most modest erosion of that is cause for serious alarm with the publican's lobby, blocking such proposals is the raison d'etre of the IVA and the LVA, anything else they engage in is just window dressing to their main function.
I'm not being cynical just for the sake of it, you've clearly given the issue a lot of thought, but I'm very much of the opinion that rather than build another level of byzantine legislation that creates more categories of licence holder, that the benefits of deregulation and application of the simple "on" and "off" licence holder types system that you suggest should be emphasised.