I think that if you want to merge it now to trunk, you should just do a refactor to move the code out, and to have the store ready for the future.
Having comments like this:
bring me to the conclusion that probably this refactor is not enough to be future proof, and probably it will change again for stripe compaction or others. So why we should merge this code now, with no real use cases?
Think about having a level/stripe compaction branch and merge everything once you've defined the right interface.
I really want to see this stuff going in as soon as possible, but I'll like to see something that uses it.