AMR wrote an article sometime back whether evolution of SOA will kill ERP.
I would think, if anything it will spur ERP backbone growth and help unlock various enterprise vendors to build better (and complete) stack for different industries, sub-industries, geographies, emerging markets, etc. that are currently unreachable due to the time and energy needed by the close systems. SOA based ERP system will create far reaching vibrant franchise ecosystem needed on successful ERP backbones to truly scale the business by reaching beyond the current markets/industries thus paying off better margins to the companies who end up having successful SOA enabled ERP backbones. Key will be around how to create and manage successful franchise.