"What AMP Caches are available?

Currently, there are two AMP Cache providers:

* Google AMP Cache

* Bing AMP Cache

AMP is an open ecosystem and the AMP Project actively encourages the development of more AMP Caches. To learn about creating AMP Caches, see the AMP Cache Guidelines.

How do I choose an AMP Cache?

As a publisher, you don't choose an AMP Cache, it's actually the platform that links to your content that chooses the AMP Cache (if any) to use."

The above is from amp.dev, formerly ampproject.org

As the dominant search engine/web portal (excuse me, "platform"), already having the largest web cache and the infrastructure to maintain it, it looks like Google therefore becomes the dominant AMP cache as well.

There is also the Cloudflare AMP cache that can be hosted on any domain, so it is easy to implement a link aggregator that gets instant article loading just like Google and Bing. Compare to the situation prior to AMP where if you wanted instant article loading, you would have to convince publishers to integrate directly with you like Apple News or Facebook Instant Articles.

Dominant AMP cache is a meaningless concept. You as the link aggregator have to have your own AMP cache to implement instant loading.

"You as the link aggregator have to own your own AMP cache to implement instant loading."

You lost me there. By "link" you mean URL?

Yes. If you're a search engine, a Reddit, a Twitter, or some other site that presents links to other pages expecting the user to click through to multiple pages, you can safely prerender AMP pages by implementing your own AMP cache but not by using Google's AMP cache.