I don't know if it would be one network, though. You'd definitely need to be able to look up data, obviously, so you could talk to the network to do that, but I think trackers would be a good way to solve some of the issues of IPFS, which means that maybe each tracker had their own "network".
I've wanted something like this many times, though, where I could help keep the IA online. If I could tell my site's visitors "help keep this site online, please donate 1 GB", it would be great.
So https://collab.ipfscluster.io/ shows how you can essentially have content distributed to followers, that may come and go, fetch updates as they will.
This sounds like a great utility indeed, I'd love it too !, over time it would make the overall network more and more resilient :D