In another thread it was recommended to always keep the original RAW files, because RAW converters improve over time, and converting old RAW files with new converters would potentially give significantly better results than what was possible a few years agoThis is definitely true, I've notice an improvement in ACR over time, and so I go back and re-convert my favorite photos every year or so to see if they turn out better. Highlight recovery and denoising have gotten a LOT better in the last 3-4 years.
Personally, I'm not worried about it, there are SO MANY images out there using Canon's RAW format I don't see any software "dropping" it any time soon.And even if the major programs did drop it, two things would happen
1: It would be very publicly announced, probably with about 5000 posts on this forum and every other forum. And someone will make the tool that turns all your RAW format photos into whatever the new format is en masse.
2: Someone would create a legacy converter that works on every platform. I mean, Magic Lantern alone creates converters for the proprietary formats that create for RAW video and HDR video and Dual ISO shots...they'd easily be able to create a CR2 converter for everyone if they made that format obsolete.
So, my conclusion is to archive them in their native format. Because then you know they are lossless. And in the future, should that change, converting them will not be any more difficult than doing it now.