Well, ProconOS will always have access to the KRC (or OfficeLite's) I/O, if configured correctly. This is because it's simply a virtual PLC running alongside the KSS in VxWorks. In that illustration, ProconOS appears to be using OPC Server to communicate with the outside world, which is reasonable -- OPC Server, if my limited understanding is correct, is pretty hardware-independent.
Under KRC2, the issue with using OfficeLite with I/O was that, running non-KUKA hardware, there was no certain way to add a (for example) ProfiBus card and be certain the KUKA drivers would work. EKX got around that by being TCP/IP, which has the advantage of being much less dependent on specific hardware configurations. RSI, OTOH, would refuse to install due to hardware dependencies (in my experience, at least), despite the fact that it had an Ethernet mode.
Since the KRC4 is entirely base on Ethernet internally (technically, EtherCat), the hardware dependence may be reduced, although I'm not sure to what degree. It would depend on to what degree the various buses (KLI, KSB, etc) are emulated in OfficeLite. If KLI is fully emulated, you might be able to install and use ProfiNet or EtherNetIP. Using a different fieldbus would require adding an adapter module, but that would in turn depend on whether the correct internal KRC bus is emulated all the way out to the host computer's ethernet ports.
Really, this is a question for KUKA service support. They should have a complete list of what I/O and option packages the latest OfficeLite will work with.