Why do you think so? ipfs is basically a distributed storage system....the only real challenge is in being able to find what you're looking for again, once it's been added to the IPFS system. Can you tell me more about your thoughts on why you don't think this would be a good integration? I'm not suggesting the calibre core has to support it, but perhaps a plugin?
LOL Also, scroll down to the section titled "IPFS can help here and now":
https://ipfs.io/#how
I mean....it's making a good use-case for calibre...lol
Edit:
Just to make the point, I can very easily, one by one, upload the files/assets I have, and then create a new column in Calibre to track the IPFS CID for each asset uploaded, and make that a link. The problem with doing this, is that it's literally a manual process, and with a library of 2647 entries (and growing) with multiple book formats per entry, this is untenable.