IF Cedar Fair decides to make major structural changes to theming or to the parks' infrastructure, WinterFest becomes much less likely. The winter season available for the conversion work is short enough, without shortening it further by basically not being able to start such work until after January 1.
Moreover, Cedar Fair is going to be on the hot seat to show they can assimilate this change and still pay dividends to their shareholders. If WinterFest was a big financial bonanza, it might still continue. If, however, it was barely profitable or lost money, I see it more likely that it will not continue.
For the record, Cedar Point had a similar winter holiday gathering...ONCE, whereupon it was cancelled and not held since. But getting people to a windy park on Lake Erie in December and early January is a far different proposition than is Kings Island's. Not to mention, where do you find employees in Sandusky, Ohio in the dead of winter?