Even without ASICs the read/decode/forward part is apparently not a big deal: you can easily saturate multi-gigabit connections with cheap cpus today. But only if you don't have to make complicated routing decisions (i.e.: select the most appropriate "next hop" for each packet).
SCION pushes these decisions to the senders. When a sender sends a packet, that packet already contains the route it _has_ to follow. ISP routes are then dumb forwarders whose only job entails:
1. Ensuring the packet is valid (including a cryptography check for the route information). While this may seem expensive, note that pretty much all general-purpose cpus today include specific hardware to deal with this.
2. Forwarding it according to what the packet says
Of course, this implies that there needs to be a "control layer" that allows end hosts to construct these routes for each packet. However, that control layer is similar to a DNS system, meaning that while not trivial it can use a hierarchical, heavily-cached approach and shouldn't be too challenging to scale.
That sounds eminently abusable.