Considering the expense of nodes, AMD will have to make due with less designs. Considering Nvidia has a no compromise compute chip in the Gx100 series and a gaming focused gp102 series, I think it is impossible for AMD to make a compromise chip that competes with either without some sort of temporary crutch like getting to 7nm first. This is not a long terms solution.
What I believe AMD needs to do is focus. That is do a pure compute card at the high end which doesn't does not get extended to the gaming market.
And something along the lines of polaris as far as pricing and target the entire market below this? So what about the high end? Ignore it and spend that time on getting this chip as good as possible as soon as possible. E.g RX 590 or 580 on day 1 and have sufficient drivers which show almost all the potential day 1. That doesn't mean AMD has to abandon the high end.
I believe the solution lies in something AMD has abandoned mostly but it will be something they need to focus on in the future and that is crossfire and mGPU.
The thing is, AMD for the chiplet design to work, needs to get their drivers to the point where crossfire works in 90% of games. That is they need it to work enough that it isn't used as a strike against them. Because of the rising cost of designs on higher nodes, there is no way AMD will be able to keep up tit for tat with Nvidia. So what should they do, focus on less designs, save that money and spend it on software development which has been a clear weakness for them(bad initial performance). Similarly crossfire support is even worse than SLI as of late which is pretty bad to begin with. Since Nvidia has removed SLI support entirely from the GTX 1660/1660 ti and RTX 2060, its a potential vulnerability which AMD can exploit if they get their crossfire performance fixed. In addition, it would help alleviate, some of these market saturation issues. If crossfire was good and well supported across lots of games, with so many owners of Polaris 480/580, AMD would have sustainable long terms customer base as soon as they drop the price of these chips over time on top of laggard buyers. The high end lately for AMD have been expensive gambles that typically don't work out for AMD.
From what we have seen with cards like Vega and the GTX 480, making a compromise chip that does everything to target the high end market leads to products very late to market having performance more along the lines of the competitors smaller and cheaper chips.These chips are extremely intensive for resources in terms of engineers which is why they come out so late.
Trying to make a compromise chips that does it all like a GTX 480/580 is mostly a fruitless effort at this point and Nvidia already learned from those mistakes. This is because making a jack of all trades cards leads to efficiency issues and extra silicon that doesn't help gaming performance. AMD high ends cards compete with Nvidia GP104 chips but have cost to build more along the lines of GP102 chips. This is not good because it puts AMD in a position where Nvidia can price them out of the market with just a few price drops. If it wasn't for the mining boom, Vega would have been dead in the water. What we are seeing repeatedly now is a pattern where AMD comes up short, far too late and the story was largely the same with Fiji and the again with Radeon VII.
Trying to build a fermi that does it all when Nvidia has products that separately target the compute market and gaming market will be all but impossible to do in the long run without a huge R and D budget. AMD will just fall further and further behind as cost go up and dilute AMD already limited resources. Under funding a project that needs more resources simply leads to a slow death. We are witnessing this with the GPU division. This is why it was right for AMD to can and sell off imageon, and cut development on ARM server processors. All the major companies making cellphone chips vertically integrate and develop their own GPU(or buy a company out right) or use ARM's reference design. Developing custom ARM architectures are super resources heavy and AMD doesn't have the budget to compete in this market, while designing CPU and GPUs. Time to market is everything and spreading your resources across too many projects will make your products late and substandard. Cutting off these expensive projects and removing resources from the GPU division to ensure the success of Ryzen(both time to market and performance) was the correct move for the long term survival of the company. But since AMD CPU division is saved, they need to start correcting their mistakes with their GPU and be realistic with the resources because what they are doing now will simply kill their GPU division.
AMD might be proud of Radeon VII right now, but it is far too late for the card to make a splash in the professional market and data center market. This is because GP100 and GV100 have been on the market far too long and combined with CUDA, it makes it very difficult for AMD to penetrate this market. Building a super computer for examples using a Radeon VII is simply undesirable because everything about the super computing market is about time to market and all the big contract have already gone to Nvidia and long since built. AMD needed something like Radeon VII to happen 2 years ago or more. GV100 was being tested in 2016 and has specs a bit better than radeon VII on top of the Cuda advantage. At this point, the next super computing cards will be looking more for next generation beyond Volta performance and have it in prototype form by the middle of 2020. Releasing hardware that is competitive with your competitors 2 years later is not good when the super computing market is all about epeen and having the fastest super computer in the world for as long as possible. Since AMD is using 7nm as a crutch to catch up to GV100, they will always be late to market since Nvidia can deliver on 16/12nm what AMD needs 7nm to accomplish. So AMD needs a 100% compute focused chip to have a chance in the long term data center market where cost don't matter as much and to have a chance to gain a performance advantage to make up for the lack of support for Cuda. They are diluting their staff focusing on too many products with their limited budget and it is making all their products late or flawed(AMD needs to be able to deliver RX 590 performance day one on the launch of Polaris).
Like Ryzen, AMD RTG needs to make less products but use that focus to build better designs and creating solutions which increase their versatility.