This means, in effect, that the plan has been scrapped.

in 是介词，表示"在...中"或"处于某种状态"。 effect 是名词，意思是"效果、影响、结果"。 in effect 是一个固定短语，意思是"实际上、事实上"，用来强调某事的真实情况或实际影响。