If I were a seller and you asked me that, I'd tell you to jump in a lake.
As a buyer - I just got my first park under contract yesterday, my biggest fear is everyone leaving, what then? Right? I think your fear is natural. Check the leases, see what they say. Moving homes isnt cheap so I can't imagine they would just move in to sell the park and then move out.
Also you should expect turnover in rentals. What does your test ad tell you? What's the demand to fill vacancys in new homes? If all of your due diligence checks out, don't let the fear of unknown scare you off. (I'm also talking to myself now)
Best of luck with your purchase.