By your math they are saving a minimum of $5k per month per deployed device.
Any network not meeting these minimum requirements will be served under existing Level 3/Limelight/Akamai contracts.
Even for Netflix or another DIY delivery case a CDN will continue to have value. A couple cases immediately come to mind: Lower first byte latency on first video blocks, then a hinted handoff to the openconnect device. Resiliency/recovery of network events, in a similar manner. "long tail" content that doesn't fit in the open onnect cache width.
A key point of these devices is IIRC they're only available to peered ISPs in one those NA IXs. Netflix is essentially converting 5-8gbs of CDN/transit expense in to $50,000 (WAG) of capital. That's what's really brilliant to me.
Once transit costs drop below $1/mbit @95th percentile (circa 2014 [1]), it's costing you $1 to transfer approx 300 gigabytes/month. At that point, the management costs associated with all of those distributed CDNs becomes greater than your transit costs. This is somewhat offset by continuously dropping prices of CDNS [2] which is as low as $0.02/Gigabyte on a 500 TByte commit.
What this does tell me is that NetFlix thinks they have an opportunity to save money on CDNs and can beat that $0.02/Gigabyte.
Bandwidth Delay Product(BDP) - keeps CDNs relevant for _downloads_ (iTunes, Software, etc..) - because everybody likes to max out their 100 mbit comcast connection, but you don't need much bandwidth to stream a show. Maybe some value for CDNs in HD or live event streaming.
[1] http://drpeering.net/AskDrPeering/blog/articles/Peering_vs_T...
[2] http://blog.streamingmedia.com/the_business_of_online_vi/201...