I was going to post this in a similar thread but I figured I should start a separate thread based on some thoughts that just came to me.
I know Lincoln grew up in the Frontier and a lot of people advocate his moving to Frontierland, but I don't think this would work for a number of reasons.
First, let's not forget that Lincoln was a President and would have lived in the White House for some years. The Main Street Opera House is done (at least the interior) in a style that is extremely reminiscent of the White House itself.
Second, let's forget Pirates. If you are in the Frontier, why would you all of a sudden be stumbling upon Abraham Lincoln as he appeared during his Presidency? The only way a Lincoln attraction would work in Frontierland is if the attraction is changed to highlight his early years such as reading a book at the fireplace, chopping wood, or some other time before he became a lawyer. Sure, it could be argued that as President, he was merely visiting the Frontier but due to security reasons I doubt that he really did this that often. Let's not forget that as President there was more pressing issues that Lincoln had to attend to.
Third, if Lincoln was in Frontierland, assuming they keep everything the same and leave him how he appeared in his Presidency, they still would have to change the final scene where the Capitol Building appears. It may not make much sense to be visiting Abraham Lincoln during his Presidency in the Frontier, but it makes even less sense that you are supposedly in the Frontier and all of a sudden you are looking right at the Capitol Building Dome.
Fourth, it makes actually more sense thematically to keep him on Main Street. As I have stated the interior design of the Opera House is reminiscent of the White House and other stately buildings in Washington, DC. But just as much as one would have to stretch their imagination (as I have just explained) to accept him as President in Frontierland, one could argue that the Lincoln seen in the Opera House is an actor from early 1900’s America doing an homage to him.
Just my two cents on the Lincoln in Frontierland issue...