Sure, that is the best case scenario. Apple using it's own servers would have several advantages including they would presumably be able to tune/seed the cached content based on superior knowledge of consumption. They also wouldn't be competing for the same limited CDN space as others.
Not to be flippant, but I recognized your name and when I visited your bio I see you now work at Netflix. You could probably find an excellent answer as to why Apple would choose to start its own program rather than rely on existing CDN colocation by asking your internal team why Netflix does the same. My guess, without inside knowledge, is it is a combination of price and performance.
I know why Netflix does what it does, I helped build it. :)
What I'm saying is that Apple is probably already doing the same thing (using their own servers in colocations). They're just opening it up to the public now.
Well, edge cache doesn't appear to be brand new (I found https://www.c8k3.com/blog/caching-in-apples-new-cache-progra... which dates from Dec 2019) but it does appear to be an analogue to programs like the one you helped build at Netflix. So while they probably have been doing this in some limited fashion (e.g. through direct outreach), it is entirely possible your own ISP wasn't included. Hopefully your download speeds will increase if/when your ISP signs up for the program.
I'm not sure what you mean that this is being "opened up to the public now". This seems to be limited to ISPs as far as I can tell. I'm not sure who, other than an ISP, would be doing 25Gb/s of Apple-content related traffic.
Not to be flippant, but I recognized your name and when I visited your bio I see you now work at Netflix. You could probably find an excellent answer as to why Apple would choose to start its own program rather than rely on existing CDN colocation by asking your internal team why Netflix does the same. My guess, without inside knowledge, is it is a combination of price and performance.