I was taking a closer look at the processing times of permits to the Army Corps of Engineers (VF has to apply with them to use the wetlands for construction), and it looks like it could possibly take a while for their plans to be approved.
CORPS OF ENGINEERS URGES EARLY PLANNING FOR PERMITS - 5/15/2014: Special Public Notice: The U.S. Army Corps of Engineers, St. Paul District, encourages project planners to carefully plan projects in Minnesota and Wisconsin requiring Corps permits. Currently, timeframes for general permit decisions, those with impacts generally less than 0.5 acres, are averaging 85 days. Timeframes for individual permit decisions, which include letters of permission, range from 4 months to more than a year, but are currently averaging around 8 months.
SourceI believe Valleyfair's permit was filed sometime in April, and if it takes until December (the current average) or later to get approved, then it might be possible for Excalibur to stay for another year (December might be too late to start construction and be done in time for the season).