There are a few things that make this an interesting moment for AMD, and the market knows it... it's stocks have been going up.
Contrary to older CPU's, Zen is a brand new architecture, built from the ground up for what the market is asking for... energy efficiency and performance. They'll no longer be handicapped either by production process (nm) or old architectures that didn't care much for energy efficiency or the myriad of modern resources and interfaces Intel CPU's currently have. If they can bring all this to their advantage they might catch up to Intel, specially because having virtual monopoly Intel's had no real motivation to increase performance more than a little bit... I'm on a i5 2500K and still don't see a reason to upgrade. AMD CPU's have more cores and if they implement proper threading, memory and motherboard support and don't waste time with silly resources like special integration with Windows 10 like Intel they could catch up.
I doubt they'll surpass Intel in general, but they could recover a niche market that is gaming, design and VR. Even if their CPUs are a little less efficient, but more powerful and take better advantage of DirectX 12 and Vulkan, they have a shot at growing again.
On the GPU side thinks are easier to be optimistic about, Polaris will catch up to Nvidia in process, wich might close the efficiency/heat gap we have today, and we'll finally be rid of old arichtecture that's stuck with us for ages. AMD has been very good at keeping on par with NVidia even with outdated resources and limited cash reserves for research. Current cards already best NVidia because of architecture on some aspects, like in DX12 and Vulkan (because of hardware async) and they have the practical experience of working with 3d memory. That said, Nvidia is also closing it's weaknesses in those regards, so AMD better use these advantages to full effect, or they won't withstand the full might of Nvidia's resources.
It would seem that on the GPU front AMD could surpass Nvidia this generation or, at the very least, stay on par (unless Nvidia surprises us thoroughly, but all they're anouncing for Pascal is on par with AMD). On the CPU this could be a return from the brink. It wouldn't bring back the golden days of AMD CPU's but it might be the start of a come back. Here's hoping they're not overhyping it.