If this new attraction will appear in the "middle of next year", and if it was going to be where Boneyard is now, then it seems only logical we'd see signs of construction by now.
Also, Earl said that "something goes out, something comes in." Now if that means in the same location then whatever is there now will have to be dismantled before the new attraction could be built. That suggests to me that if a major attraction is being replaced we'd see signs of work by now. Since we don't see signs of work, then we can conclude that either the switch is something super simple (doing away with Blues Brothers and bringing back Rocky & Bullwinkle) or it will happen to an attraction that can be replaced quickly (Hitch, Beetlejuice, or Makeup).
Of course, if the attraction coming in won't be in the same location as the attraction going out, then all bets are off. For all we know, the new attraction could be being built even as we speak in the old Herc & Zena theater and when the time comes the "old" attraction will just be shuttered.
That's as far as my cool, logical deduction takes me. OTOH, I almost flunked logic in college.