Until someone creates a well-thought decentralized CF alternative from the ground up, which solves bad actor, slow and unstable node problems, with clever incentives, et cetera et cetera, we'll be stuck with centralized solutions.
P2P is a lot of things, but latency optimized is definitely not it. Things like DHT involve lots of hops, you also can't control the quality of nodes.
I understand why you thought of blockchain when i said p2p has bad latency. Blockchain of course has latency that is beyond terrible, but that is not what i was thinking of. I was thinking of bit torrent. Bit torrent is amazingly fast for a bulk download once it gets going, but is really slow to get going. Even just figuring out which nodes have your files is unacceptably slow for this usecase with the current distributed technologies (DHT). CDN is all about serving small static files with very low latency. P2P simply involves too many layers of indirection to work for that use case. I also don't see a way around it without centralizing things.
As far as security goes. Its actually not that bad and largely a solved problem using combinations of digital signatures and hashes. (Preventing DoS is a bit trickier although i think there are solutions for that albeit probably ones that prevent using geolocated nodes)
It is solvable, but any solution that spreads resources out across many different targets in the DHT is slow. Basically anything that was inspired by BitTorrent, but isn't BitTorrent itself does this, because they get overly excited by deduplication of data.
CDNs try and solve the "speed of light is too slow" problem. To make sense they have to respond to queries faster than a central server would (or a small number of geodistributed servers would). Otherwise the CDN does not bring value.
DHT traversal is usually log(n) in number of nodes. It seems unlikely that will ever be fast enough to compete with just hosting your stuff in one central data center even if your data center is on the opposite side of the earth.
This is a use case where 20ms can determine if the solution makes sense or not.