You're also talking about systems 20,000x larger than what The DAO contract was [1]. The total DAO contract is roughly 2,000 LOC by my estimate [2].
IMO it probably won't be overly onerous to develop reliable contracts of this size using many of these techniques. It's just so few people have the discipline to delay implementation for design and planning at the level required when it needs to be bug free. Most software developers have no training in how to even begin designing and developing using these techniques.
[1]: Shuttle's primary flight software contains 400,000 LOC http://www.nasa.gov/mission_pages/shuttle/flyout/flyfeature_...