Canon applied for a patent application on a 70-300mm f/4-5.6 lens in March 2011. Presumably, this is an update to the consumer grade line of 75-300mm non-IS lenses. There’s no mention of image stabilization in the patent; however, that doesn’t necessarily mean that it couldn’t be an IS lens.
These are the current consumer zoom models in this range:
The other line of thought is that a new 70-300mm f/4-5.6 lens with image stabilization could replace the existing mid-grade lens as a cheaper/lower model. The current 70-300mm f/4-5.6 IS lens is heralded as an excellent non-L lens that approaches the image quality of the L-series. In this way, the old lens competes with the new and pricier EF 70-300mm f/4-5.6L IS lens, which is nearly 3x the price of the non-L version.
As with all patent applications, it’s no sure thing that a give invention will make it to market; however, lens patents seem to have a better track record of predicting future products than other new concepts like fuel cell batteries in DSLRs.
If you want to check out the patent for yourself, I’ve made a PDF version available here: Canon 70-300mm Lens Patent
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