Those are good questions to be asking, and it's good that you've really thought through your shorter and longer -term post MBA goals.
My feeling would be to include both, the short-term plans as you described them, and the longer-term entrepreneurial vision... especially if the long term vision makes sense in some way based on your career path to date/before then. You want your story to flow-- showing that your past experience leads to the MBA, which leads to your future (short and long term) post MBA goals. Even if there are changes along the way, there should be some semblance of a flowing story and there should be things you are bringing from each step to the next one (skills, experiences, etc).
Overall you want to be as honest as you can, as generally people come across as more genuine and your writing is naturally stronger, when you write from the heart about why you want the MBA and how you envision your future career path. What I often suggest to applicants is to do your first drafts without worrying about the admissions committee or what they are 'looking for' etc... you can always edit/improve from here, but it takes the pressure off and lets your genuine voice come through. It's up to you how specific you want to be about exactly what you intend to do shorter term but it's actually fairly common to have shorter term goals as well as longer term entrepreneurial vision and depending on what that is and how you set it up, it could even be a way to provide something unique/memorable.
I hope that's given you some food for thought! If you have any interest in discussing further we do offer free 30 min consults to provide profile feedback and answer questions. (If interested, you can sign up at http://www.mbamission.com/consult.php
Good luck to you!
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