The "elephant in the room":
While LISP et al appear to solve some problems, when you look at it
just the right way, the real problem is - how do you multihome, and
detect, handle, and respond to failures on one of many paths
available (i.e. "route around" the outage), in a scalable fashion?
In BGP with PI, i.e. using BGP for multihoming, the state is carried
via BGP.
In LISP, the presumption is that the mapping stuff handles the state
- but does that differ much from the BGP solution, other than moving
the problem somewhere else? The state is still needed, and needs to
be propogated in a timely fashion.