Well, the days of Canon/Nikon taking their own sweet time to update lenses is likely drawing to a close. They could get away with that before, since there was no real competition. Sigma and Tamron have not been taken too seriously by most enthusiasts/professionals for their inconsistencies in build quality, autofocus or whatever. This information would filter down to the average consumer, causing them to stick with OEM products unless budget restraints were critical. If this current rise in quality is sustained and not just a momentary aberration, this too will become well known and no company will be able to rest on their laurels. This is of coarse good for all consumers. The fact that Sigma is not just meeting, but improving over the OEM brands for significantly less money is amazing. For now, it is just in their high end models. I wonder if Sigma will be able to compete in the lower end of the market as well. That will really make Nikon and Canon take notice.
To steal a line from a previously mentioned "restaurant", I'm lovin' it!
I think you fundamentally don't get Canon's position. They are a multi billion dollar international corporation and are not overly interested in selling tens of thousands of lenses, they are into selling millions of cameras. Now the P&S cash cow is drying up they are repositioning into the C line, which is probably the only thing keeping any R&D going for us high end body stills shooters, and surveillance cameras hence the ultra low light sensor video R&D etc. They don't see Sigma or Tamron as competition because they aren't, they are comparatively small companies that sell limited quantities of niche products that you need a Canon (or Nikon) product to use, just like ThinkTank, or Adobe.
I think, fundamentally, that Canon's position is to turn a profit. The fact that Canon Inc is a more diversified company that doesn't derive all it's income from cameras and lenses is irrelevant. While I will certainly agree that it's unlikely that the board of directors are sweating bullets and pulling all-nighters over the rise of Sigma and Tamron, I can assure you that they, or at least their subordinates, look at market share in all divisions with great interest. My point was that if Tamron and Sigma, which most certainly are competitors to Canon, continue to develop high quality lenses at much more reasonable prices, then their market share will certainly increase as word gets out. So far, Sigma is only seriously competing at the higher end of the market and so it could be argued that they are in more direct competition with Zeiss (doesn't that sound funny?) than with Canon. But as Sigma's reputation improves, then its products will become more than just niche lenses and lower cost alternatives for the financially impaired.
Next week we shall discuss sensor development (and profits there from) vis a vie Canon vs Sony