I think a good comparison would be a website + hosting. Traditionally, many "agency" type business have designed a website and then hosted it. "Unbundling" would be turning over the source code and letting the customer find hosting at the right price. (At my last job, we did have an agency make our website, and then we hosted it along with the rest of our infrastructure. Incremental hosting cost for us? $0, since we just ran it alongside our internal admin tools, which we were already hosting.)