CityFibre and Cuckoo

Is Cuckoo planning to use CityFibre infrastructure to provide FTTP to customers? They are wiring up my neighbourhood in Maidenhead and a few suppliers are offering 500Mbps at a price about 25% higher than my current Cuckoo 70Mbps FTTC account. I am very happy with Cuckoo and would prefer to remain, but 500, or even 900, Mbps is very tempting.