The problem isn't really being competitive with Nvidia, they will manage that no problem just like they have in the past when even further behind. The BIG problem is that even when they are competitive and offering much better bang for buck most people will still buy Nvidia over AMD to a huge degree due to brand power. We last saw this when the HD7900 cards were beating the GTX670/680/770 and noticeably cheaper, the GTX cards were still outselling the HD cards by a large amount.
Just a note, that's roughly the TDP for a Vega 64 liquid set to turbo (OC) mode in drivers, it's probably listed as a worst case scenario. Out of the box TDP for the regular V64 without any tweaking is 220w.