Who needs BPM?

BPM should be an organization wide initiative not a department specific or systems specific. This should be the real motivation for any company planning to invest in BPMS. All the business processes of the organization have to be discovered/implemented/migrated/automated to BPMS platform. This has to be the end state or at least should be an ideal state for the IT division of a company.

Workflow Systems:

Although BPM systems have its roots with Workflow systems, BPMS is definitely not an extension of a workflow system.
Workflow is no substitute for BPMS and BPM is rather looked at as systems-to-systems technology.
Also workflow is specific to a system/ collection of systems, but does not collectively represent a domain.

EAI/ESB:

With the advent of SOA, I feel the debate of whether we need to use ESB or existing EAI system becomes nullified.
SOA can be implemented either with EAI/ESB or even without these.
In my opinion BPM can be better sold with SOA rather than with ESB. ESB is perceived both as a product and as architecture. Let the customer decide whether he needs an upgrade from EAI to ESB with necessary cost justifications.

BPM complements SOA and vice versa.