Going through the numbers...
Congrats to AMD, you advanced all the way, to re-architecting the efficiency of Polaris, almost. Going by the numbers, using transistor count as a rough estimate as trying to compare silicon node advance is a fucking nightmare, the rx590 is about half the transistor count of an Rx 5700 Xt (screw you AMD GPU marketing!). If you go by performance numbers of GTAV, Total War Three Kingdoms, etc. the 5700 is, about twice as fast as a Polaris rx 590. And when it comes to power consumption, well that's similar to Polaris for double the performance! Except the 7nm pretty much accounts for all of that advancement, as it nominally takes up half the power. To sum: If you doubled a Polaris 10 and taped it out on 7nm, the performance overall, and per mm, and per watt, would look a lot like a Navi whatever the 5700 is.
Polaris was released three years ago. So, sure, AMD rolled back the de-advancement (gamewise) of Vega. And the larger caches and a few extra features will help RDNA performance wise going forward. But close to no efficiency gains in terms of performance per watt or performance per transistor after three years, and no advanced hardware features the competition already has, feels apathetic at best. The only way I can call RDNA a success is if it's a stepping stone towards chiplets. Going by the diagrams released, it very well could be the intention. Just like with Zen 2 there's self contained blocks that have their own cache and don't need access to each other. In fact each block has it's own memory controller, an advancement over Zen 2 that would be needed for GPU chiplets.
But are chiplets actually going to come? Is Infinity Fabric going to get such a massive bandwidth boost within a year or two that AMD can produce a chiplet based GPU? I don't know. It would be worth it, no doubt of that. Design costs would plummet, scaling would only be bound by bandwidth and power supply constraints (600 watt GPU anyone?). And most importantly scaling to bigger GPUs would become much closer to linear costwise, allowing AMD to drastically undercut Nvidia and Intel in price. Yet getting enough bandwidth for a GPU chiplet is a huge, huge, huge issue. Getting to CPU chiplets was already hard, AMD is the first to do it. But GPUs are yet another, even larger mountain. And unless AMD plans on scaling it soon, or RDNA has some easy issues holding back performance, it just doesn't feel like much of an advancement.