Re: Speed Vs Stability
Define 'Core router' please?
For example Cisco ASR9000 is not a core router, by a (nautical) mile.
True core router doesn't need to know anything about a VRF. If it must absolutely positively speak BGP all it sees is another AF prefix in BGP, not in the forwarding table.
Speaking of code bloat - (again for example) ASR9000 can have selective packagages loaded, you can cook your own (smaller) installation from a large tarball. Also every flavour of line card out there needs to have the code to support it. Also imagine every MPLS flavour (there is more to life than VRF and EoMPLS), OTV, VXLAN, LISP, etc - that is all code which not every ISP might use, but someone out there uses. It adds.
Add the things like HQoS and the likes and see why the vendor might want to add those as different line cards (ServiceEdge vs Transport) and charge appropriately. The NP/NPU in a router line card can't simplly be replaced by a Xeon chip and hope it will do. Not likely.
Yes - agreed - the memory thing is shambles. Why do I need 8G RAM on ASR1000 in order for the RE to have only 3G allocated to the IOS-XE process is beyond me. (I know, it runs Linux underneath and that takes RAM, but still)
Cloud VM - good luck with getting the throughput of 120Gbps full duplex from a VM. There is a place for VM-based routers, but they can't replace things like Proprietary Silicon or Merchant Silicon when it comes to performance. Also Juniper vMX, Cisco XRv and Aristo vEOS are nothing new, Cisco CSR is quite a few years old.
Regards automation - Ansible, Netconf and Yang, Napalm, expect script over SSH if you are so desperate and if the kit is old, nothing new here. But that's the easy bit, the hard bit is the orchestration. And making network engineers think like DevOps (yuck, hate the word).
Disclaimer: I do not own shares in Network vendors, distributors, etc.