There will be (or actually is) such a cable. It's not without good reasons that the XT is compatible with Cambo lens plates. To make it work, an update to the back's firmware need to be made. We may have to wait a bit for that - the world seems to turn slower these days - but it will come. Thus you'll be able to use your WRS alongside the XT whenever more shift is needed. As there isn't any electronics in the WRS, there obviously won't be any data transfer. But still the X-shutter is a joy to use, reliable and more precise than a Copal can ever be.I am German and currently also live here. That the XT did not sell well in Germany is due to the fact that only KIT's were for sale here.
But for me as the owner of various Cambo's, an IQ4150 and IQ4150 Achromat, this is absolutely uninteresting. Furthermore, there is still no cable which a new XT lens e.g. can control on a Cambo via IQ4 and I can not be 100% sure that this cable will even exist.
So it makes no sense to me at the moment to invest in an XT system and I don't find it surprising that the XT should sell badly here in Germany.
For me personally, I see the actual profit in the new shutter.
BTW: To use the lens panels safely and avoid damage to the connectors, the WRS body needs to come back to us, to machine a small cavity into it.