I wouldn't say everything, but these kinds of games always have long term plans as to where they are going. Of course, things happened that changed the plans somewhat, but we would be naive to think they wouldn't still use as much of what was already there as possible.
Someone actually said, long ago, that a year's worth of content was already in the works for this game. Hell if I can remember who it was now though. There have been so many delays and changes that it is more than feasible we are still waiting for that stuff.
The inns are a good example. This is something the original director had already planned for us, but was unfinished. Now under Yoshi, it got finished.