AMD will be releasing a new architecture in 2016 and will use 14nm process. Hopefully Jim Keller's team will close the gap.
AMD is great on paper, almost never delivers. Every time they managed to deliver something good (K6, K7, R700) it was sudden and without much PR, you could even say it was a total surprise. If anything AMD has a long history of sitting quiet when they actually have the goods, and producing nice slide decks before usual flops.
I remind you that It was AMD who created 64 bit x86. This is why it is originally called (and still sometimes rightfully called) AMD64. I mentioned Jim Keller because he is the co author of x86-64 instruction set specification and lead architect of K8 (opteron) processors. He went back to AMD and working on the new Architecture since 2012. It is true that last 8 years was mostly disastrous for AMD, but I wouldn't count them off so fast, especially if they can ramp up on 14nm with a high IPC design. Time will tell.
But they took their eyes off the ball, bought ATI, took 4 and a half years to update their microarchtecture, and the first shipped K10h chips had a bad TLB, requiring them to stop shipping until the next stepping fixed that 6 months later.
I really liked them in that heyday, and, oh, back in the 486 DX4 days, but given their many decades losing corporate DNA (I'm sure it's still true they haven't in the long run made money for their shareholders), and their having to sell their foundries, it's doubtful they'll again be a big player.
For example, the Nintendo N64 game console had a MIPS64 CPU.
As I understand it, this was true for "Big Iron" AMD64 sales, for one thing, AMD had a whole year's head start where they were the only ones selling it, and then Intel played catch up for a long time. For multi-chip machines, not until Intel had their own version of the Hypertransport + local memory controller architecture.
I believe what you're talking about only happened in consumer grade chips, although I know HP for instance found a way to sell AMD based consumer systems, my parents bought one in 2004-5.
Intel's "Core 2" CPUs scrapped the Pentium 4's NetBurst architecture in favor of an evolution of the Pentium M architecture (which was, in turn, an evolution of the Pentium III architecture), and Intel was competitive with AMD on the desktop again. Nehalem brought on-die memory controllers and QPI (Intel's HyperTransport-alike) in late 2008, which made Intel the performance champion on multi-socket servers. AMD's Bulldozer architecture was dead on arrival in 2011, and AMD never recovered from that.
Maybe AMD will pull a rabbit out of their hat with Zen...
Comparable performance to the GTX 970 at merely twice the price? Meh.™
The question for consumers is: why spend >$400 on a card optimized for low-setting play at 4k? Especially when it's a marginal visual improvement over 1440p? Instead, with current-generation cards, players will rather use a lower resolution and higher settings.
Playing as a marksman in Verdun (http://www.verdungame.com) is amazing in 4K.