My prediction:

The latency will be top-notch, but only if they strictly limit total traffic. So, streaming will probably cost way too much for normal people, unless they can contrive to cache copies of the absolutely most popular stuff on all the birds. Then, everything big but not cached will be super expensive, throttled, or actually forbidden.

Of course they will charge the publishers for caching, by spot auction, and the publishers will use a good chunk of their allotment to cache ads.