It was projected that online sales would overtake traditional retail within a few years.

overtake 是动词，由前缀 over-（表示"超过"）和动词 take（"拿、取"）组成，字面意思是"超过并取得"，引申为"超越、赶上"的意思。这里指网络销售在数量或规模上超过传统零售。