Not sure if its in aid of bringing some of its customers out of the below USO or if it will be something they'll look to provide all customers on... however they have said pricing will be the same as its current ADSL based service.
I don't think this will alter the USO thinking at all. If a property can achieve 10Mbps through fibre, the government won't care whether the owner opts for an 18Mbps service or a 40Mbps. They won't care if the owner opts to stick to ADSL at 1Mbps either, because the property still meets the UFO qualification - which is all about availability, not about actual speed.
I can't see them being able to move all their customers onto it, I don't think there's enough capacity at DSLAM's for it.
IIRC, to qualify for the 18/2 package, the subscriber must start with an ADSL package below 3Mbps, although that might have changed to 2Mbps. Therefore Sky won't be able to put all their customers onto this product.