WSB on prem - future versions and backwards compatibility

Hi,

I am thinking about implementing WSB 1.0 on prem at our company.  

If I my clients and consumers connect to the Bus using tcp and therefore require Microsoft.ServiceBus.dll reference.   What happens when a new version of the Service Bus is released and I upgrade my central bus?  Will my existing clients and consumers still work and still be able to publish and listen via the old dll?   Or will I need to upgrade everything in one hit, and retest everything!  

Thanks