The main problem as I see it is that Canon don't really have any real development momentum (or budget!) on higher resolution processes. They outsource almost everything except for the larger format sensors.
The biggest difference between the others and Canon is that all the other manufacturers are all dominated by their small-sensor image sensors sales, that already now are manufactured at 90 and 110-130nm metal processes on 300mm wafers. Panasonic and TSMC will start volume shipping of sensors made on 65/45nm rules in Q1 2013. Lower mask resolutions than 130nm are not enough to land you any sales any more. Most cellphone and compact camera sensors are manufactured at those levels now, and have been for the last few years. Also consider the fact that some of the others have very large yearly revenues from logic CMOS processes at 45, 32 and even 22nm levels. All of those markets are areas where Canon totally lack any type of experience. Canon outsource all more advanced fabs on their camera bill-of-materials.
The Digic sensors are made by UMC http://www.umc.com/english/class_300/index.asp, and were designed by Texas Instruments http://www.ti.com/lsds/ti/apps/videovision/end_equipment.page
The memory is most often made by Samsung http://www.samsung.com/global/business/semiconductor/product/consumer-dram/overview
The memory/Digic package-on-package mount has to be outsourced, since Canon cannot do it themselves, and it is believed that UMC does the mounting too.
Other peripheral control and logic chips are TI, Mitsubishi, AD and Fairchild.
Going from a 500nm process to 180nm is like going from a 10MP FF camera to a 70MP camera in one generation. This means some really noticeable strains on the process, especially since the CMOS manufacturing process isn't as forgiving as just "taking pictures". You cant "scale to web size" and sharpen in post when you're making CIS wafers.
What you're basically asking from your equipment is to all of a sudden provide compact camera type linear resolution in a FF lens projection coverage - something almost unthinkable in the normal photographic world. The process has to be precise, to a degree where every single contrast and item on the new 70MP image is equal to or better than the 10MP camera - per pixel. In normal photographic resolution usage, we just want the final output to be good enough, which means that we downsample most images - we seldom deliver full-res images to the customers, and we seldom use full-res images in our own output.
Going from a 350nm mask to 250 and then 180nm and 12" wafers was a BIG step for most CMOS manufacturers, and most other manufacturers are a LOT bigger than Canon in this area.
So it's not that Canon COULDN'T do it. Even really small (in the imaging field) firms like STMicro can do it by stitching, and thereby tripling the unit prices. For Leica this isn't really a problem since the total BoM on a M series camera is most certainly lower than 2k USD. This gives a healthy margin up to the projected 7k USD end price point.
This isn't what Canon does. They live on volume, not on extreme margins.
Sure, it's a big step. Which is probably why Canon has held onto their 500nm process for so long, and pushed it to the limits of it's capabilities in recent years. We aren't necessarily talking about Canon making the leap from 500nm to 180nm in one single generation, all or nothing style. As far as I understand Canon already uses 12" (300mm) wafers, so there wouldn't be a need to "switch" to a larger wafer. I gather that they have been producing scanners capable of 90nm manufacture since 2008, so that is not particularly new technology either. Even 180nm processes for CMOS image sensor design are relatively new, and while other manufacturers have already moved much of their CIS design to 180nm, as you stated, it was a VERY COSTLY endeavor that has, in some cases, and very well could, in other cases (Sony?) put them in unstable financial predicaments. I figure Canon will put ONE part on the new process, a low volume part...say, a 46.1mp megapixel monster sensor in a body priced around $5k - $8k a pop? It doesn't even sound like that sucker will be released any time soon, end of next year, possibly later? I wouldn't exactly state that Canon is racing towards a 180nm design and fabrication process for their CMOS sensors at breakneck speed...
All things considered, Canon is not the only IC manufacturer or lithography systems producer or even DSLR company in a bind. Even Sony, the giant it is, is struggling, with numerous bankruptcy rumors floating around. The worlds largest semiconductor manufacturer, Intel, just recently missed estimates and is down in revenue, particularly for larger desktop CPU's as consumers look towards cheaper devices to fulfill their computing needs...Intel may be behind ARM, but that doesn't mean they are inevitably doomed to fail in totality in the near future. Most of all that is thanks to a shitty economy, and not a lack of competitiveness or capability.
Finally, I'd like to know where you get your information. How do you know TI designed the DIGIC sensor, or that UMC manufactured it? According to Canon, Canon themselves
designed the DIGIC sensor, and as it stands, I cannot find any explicit information about who actually manufactures them, although Canon generally stands by their "Made In House" mantra for their critical components...sensor and processor. It does not surprise me if the memory chips were made by Samsung, and there is actually some direct evidence for that (link below). Same goes for peripheral control and logic chips, wouldn't be surprising if they were manufactured by other companies, however there is still no definitive information available about who manufactures what that Canon uses in their DSLRs, which makes the explicit nature of your proclamations of "nothing is made by Canon" a bit suspect.
The only piece of evidence I was able to find about DIGIC's design and manufacture was on Wikipedia:
DIGIC units are made by Canon and used in its own digital imagery products.
I call your claims about the general source of IC's used in Canon cameras into question, particularly regarding DIGIC. Unless you can produce some solid evidence that clearly indicates Canon does not design and manufacture their own DIGIC processors, the facts currently seem to indicate Canon designs and manufactures them. DIGIC itself makes use advanced fabrication processes. This technical analysis
of DIGIC 4 clearly demonstrate it used 65nm fabrication technology, and also indicates it does use Samsung memory (not surprising), in a PoP design. At the very least, they certainly seemed to design the DIGIC 4
Canon Inc unveiled two astonishing features of its in-house designed "Digic 4" image processing LSI for digital cameras to Nikkei Electronics at a new products presentation Sept 17, 2008.
Canon's lithography units are capable of package-on-package and even 3D CMOS manufacture, so I wouldn't be surprised if it was Canon who manufactured the processor and packaged it with Samsung memory.