Navi has always been discussed as a midrange replacement, so that's RX580, RX590 and both RX Vegas replaced. And by extension, no, Radeon VII isn't be replaced just yet, but I think it will be by the end of the year or Q1 2020.
Based on nothing more than pixie dust and wild speculation on my part, I think the leaked RX 3080 specs are for a cut-down Navi 10 die, which means a full-fat Navi 10 die could be waiting in the wings. If cut-down Navi 10 is rumoured to be Vega 64 + 15% performance then a full-fat Navi 10 could be Vega 64 + 25% performance or higher: that's Radeon VII territory. The only thing stopping AMD from releasing it sooner is the 16GB VRAM precedent they set with Radeon VII - how to you get 16GB GDDR6 onto the PCB? Because you know if they drop down to 8GB then there will be a *********.