I don't think anyone is buying Cisco-on-AWS at anywhere near the same volume as Cisco gear in its heyday. It's likely for applications where traffic throughput is low or unimportant — e.g. training labs, etc. These are likely applications where it would have been cost prohibitive to buy a "real" Cisco router.

I'd be pretty surprised if people were running an actual large production network on Cisco-AMIs-on-AWS.