The majority of the IT budget (over 80%) is typically committed to supporting the existing infrastructure and applications. Even though adopting SOA brings substantial value over the long term, the short-term impact actually increases the support cost in two ways.
First, IT organizations will need to procure additions infrastructure components such as the Enterprise Service Bus, Registry/Repository, SOA Manager, SOA Governance tools, etc. Products like these not only requires upfront initial investment, it also adds one more layer of abstraction (hop) in the existing environment impacting the end-to-end performance.
Second, the support organization shall need to increase headcount and hardware infrastructure to support this next generation of infrastructure.
Even though most of the existing packaged applications are re-architecting their solution to run on the SOA platform, we are still years aways from wide deployment of these next generation applications.
It for this reason, it may make sense for the packaged application vendors to actually focus on retrofitting their previous versions of applications with the SOA infrastructure such as replace proprietary work flow by BPEL or XPDL, service enable (better) some of the business processes/services. It should be done in such a manner that the developers could still use the existing (proprietary) tools, keep the current functionality as is, limit functionality changes and roll this out as a patch release for the existing ERP, CRM applications.
This approach shall accelerate the adoption of SOA within and enterprise. In addition, enterprises shall be willing to pay incremental support to get this capability, a win-win for both the vendors and their customers.