This is going to be a “How long is a piece of string?”. Each ASN will be unique, and even within any large ISP, there may be many OCA deployment sites (there won’t just be one for Virgin Media in UK) and each site will likely have subtly different traffic patterns and content consumption patterns, meaning the OCA deployment may be customized to suit, and the content pushed out (particularly to these NVME-based nodes) will be tailored accordingly.

Since the alternative for an ISP is to be carrying the bits for Netflix further, the likelihood is they’ll devote whatever space is required because that’s much cheaper than backhauling the traffic and ingressing over either a settlement-free PNI or IXP link to a Netflix-operated cache site, or worse, ingressing the traffic over a paid transit link.

Meanwhile, on the flipside, since Netflix funds the OCA deployments they have a strong interest in not “oversizing” the sites. That said I’m sure there is an element of growth forecasting involved once a site has been operational for a period of time.