Using scaling, you can play a lot of them at 1080p res with high settings on a 2500u laptop with DDR4-2400 memory, using native 720p, scaling and sharpening up to 1080p. The performance is quite good and so is the image quality. I expect that the experience on a 4300g with DDR-3200+ is markedly better, mainly for the much more capable CPU cores.
However, I doubt that we're going to be seeing north of $50-$100 (new) class GPU performance in an APU ever. iGPUs are, for the foreseeable future, always going to suffer from three things: Memory bandwidth limitations due to the VASTLY different needs of the attached CPU and market that it plays in, Thermal/Power limits that are significantly lower than a dGPU because it has to share with the CPU cores, and finally, limited die space as it makes no sense to make the CPU package massive by attaching an overkill gpu section that would just be starved for bandwidth all the time anyway. DDR5 (at its max JDEC spec) won't fix it all the way, but, it's going to deliver what is effectively the same bandwidth as the first gen XBox One had from its EDRAM cache (a touch over 100GB/sec) , which was faster than the main system RAM (68GB/sec, similar to the minimum DDR5 JDEC spec). That should give you something useful for most games at 1080p.
Since Cezanne won't be on a markedly better process (though it will have some improvements), and since it will continue to use VEGA for the iGPU, I don't expect Cezanne to be revolutionary with its performance. With CPU cores that have higher ipc, it's likely that they will need fewer Mhz to achieve the needed CPU core performance for games, meaning that there will be more thermal/power envelope left for the iGPU section, which should help. With a further improvement in the N7 node, its possible that the gpu can run even faster. I doubt that it's going to get any bigger. I doubt that DDR4 will get notably faster.
Like I said before, if you want the absolute best iGPU performance in a micro ITX case that has no PCIe slot, then the 4700 is the best you can do. It'll give you essentially just short of RX 560 performance in most games. If you can't afford that, there are lesser parts on the stack. IF you don't have to live in an ITX case, why are you complaining when you can get a 3100 and a used 560/570 for about the same money and have something that is MILES better for gaming?