Although the Cell Theory is widely accepted and well supported, what might happen to cause it change?

By doing more research.

Explanation:

The cell theory change with the passage of time by doing more research about the cell. The final modification of the cell theory done by Rudolf Virchow in 1855 on the basis of his new research and findings about the cells.    With the passage of time, modification occurs in microscope which enable the scientists to find different parts, organelles and features of cell on the basis of which scientists modify cell theory with the passage of time.