The problem with ESBs in my opinion is one of tight coupling; all of these distributed systems that know about and depend upon each other. The solution to this is to loosen coupling whilst formalising interfaces/contracts/schemas, with a design that enables versioning and mandates graceful evolution. The modern version of ESB is an event based (note: this does not necessarily and probably does not mean event sourced) architecture built upon a distributed, append-only log that is ideally fed directly from a database transaction log.
