This is likely the best specification for CR2
http://wildtramper.com/sw/cr2/cr2.html
But you are worrying about something that today makes zero difference. And if some day it does, then you can can convert in a few hours (I assume computers will be faster then)
... I'll deal with the problem when it happens. Canon is not going to disappear tomorrow and even if they did your current software will continue to work for years, giving you time to deal with converting to whatever is popular at that time.
Like I said, only the OP can make that decision based on their circumstance. I was offering additional info so that they can make a more informed decision.
Two other things, though.
1) I am worried about file formats being supported
today. I don't worry about them changing in the future. I am absolutely resigned to the likelihood that I will be converting all my photos at some point. It will be a chore, and you are right... it will be automated. I've been using computers for a long time and have seen several formats come and go. Formats that I used to use. However, because CR2 is a proprietary format.... there are applications
today that may not support a particular Canon camera.
For instance, Capture One occasionally bumps up against propriety RAW formats. When a new camera is introduced - if the RAW format is modified from the previous version - then until that camera manufacturer shares the documentation of the format folks using the software complain that their new cameras are not supported. And Capture One has to explain that until they get the documentation from the camera maker there is nothing that they can do.
This can be a problem for any 3rd party developer. It may or may not be problem for you or the OP. Only you and the OP know what applications you use. Or are likely to use.
2) With respect, I believe that your statement "...so few people are using DNG..." may not be quite on the mark. Lightroom is used by many many people, folks who are using Canon, Nikon, PhaseOne, Mamiya, Leica, Sony, Fuji, Konica-Minolta, Kodak, Lumix, Hasselblad, Ricoh, Olympus, Pentax, Casio, Contax, Samsung, Sigma, Leaf, and Epson cameras. Have I missed a few?
Several of these camera makers can save direct to DNG rather than their own RAW format - and some use DNG as their native RAW format.
The default format for Lightroom is DNG. So - with all those people using all those cameras above and using Lightroom I would guess/hypothesis/venture/opine that there are at least as many people using DNG as CR2- if not more.
But that is just my personal opinion.