The Radeon VII actually has less compute units than the Vega 64 which meeting the transistors reduction results in a very tiny die. Be sure that AMD will release the RX 6XX generation or whatever they call it, with will definitely feature a bigger number of compute units than the Vega 64 in a bigger die than the Radeon VII one and with GDDR6 in less quantities, resulting in definitely better performance per dollar cards than Nvidia ones, specially better than the RTX which have an extra cost due to the raytracing dedicadted hardware.
Anyways, the Vega 64 has a great value and is one of the best performance per dollar cards today, the next generation Vega cards are probably more than half a year away and if it is about talking about the future, Nvidia will have at least the 10nm process for the next year (as it was planned for the RTX card but was delayed and hence we got them manufactured at 12nm) and if rumours of getting Samsung's 8nm process instead, then Nvidia will again be far away for AMD in the high end.