Thats the problem though, due o the windows monoculture all other cpu archs have gone under, even the last holdout in the consumer market, Apple with the IBM Power4 derived G5 gave up and went to x86. The only place you're seeing other archs these days in the consumer market is in stand alone devices like game consoles like the Cell in the PS3.
Nviida already has the ARM based Tegra platform
http://en.wikipedia.org/wiki/Nvidia_Tegra but you won be seeing that powring anything more powerful then your next cellphone.
As far as my stated 5 year mark, yes, that is an eternity in tech years, but with curent trends the CPU is becomming less and less important, while the GPU is becoming more and more essential. I do't see why the couldn't though have a version of the Nano die shrunk between 55-45nm and at least dual core running 2.5Ghz within a year, which would at least get them in the door at the low end with the Pentium dual core a few of the low end C2Ds and the AMD X2 line. The would be able to hold onto their gpu position for a while as well to remain profitable while they claw their way up. The real challenge though is if they can get it into the OEMs, nvidia has had little trouble getting their GPUs and chipsets into the OEMs for the last few years, I've seen more of them recently there then I've seen Intel GPUs and AMD gpus when poking around the laptops at the local worst buy.
But seriously you don' think t'd take close to 5 years for them to get a cpu that would be within a few flops oft the best that AMD and Intel have to offer at the time? By then we'll be up to 12-16 core CPUs pushing something close to 4.5Ghz a core. It's not something anyone could build over night.
Maybe someday soon we'll get multicore multicore cpus that will have several different archs running oon the same die ith some level of interpreter that decides what arch to execute what code fore some truly amazing cpu power. But alas, I think the difficulty of making such a cpu will leave it an infeasible pipedream...
No matter what it's an uphll battle for both nVidia and VIA since its now much harder to pull out an antitrust on Intel for monopolistic practices since AMD bought ATI. The only thing we can hope is that AMD has something up their sleeve to retake the cpu market and maybe a new chipset that can give us at least 4x16xPCIe slots, or even better, a 7x16xPCIe chipset with 2x CPU sockets, anything to get them more market space ahead of Intel. Just think if you could get a 14 way crossfire mobo with 2x 4-4.5Ghz OCd quads and 12Gb of tri channel DDR3. Sure theres no real reason for it, but it would get AMD more much neded advertising all over the web on various tch forums and it'd allow them to just brute force games like Crysis Warhead into actually running lol.