The 26-year-old midfielder, who is out of contract with Liverpool next summer, has enjoyed a fine 2016; first by really coming to life under manager Jurgen Klopp, before then emerging as one of Wales' best players as he helped his nation to a Euro 2016 semi-final this summer.
But his future on Merseyside remains up in the air it seems and Swansea City - where he began his career - have been linked with bringing him back to South Wales.
Allen has really only shown signs of promise in the past seven months of his four-year stay at Anfield, having joined for £16 million under Brendan Rodgers in 2012, and Nicol believes that Liverpool would certainly sell him if a satisfactory offer is submitted.
Asked by ESPN if he could join Swansea, Nicol said: "I think if the money's right, then yes. He has been a bit-part player during his time at Liverpool. He's been good, he's been bad and he's been indifferent.
"He had a fantastic Euro 2016 with Wales and that really pushed him into the shop window. So if the money's right, I don't think there's any way Liverpool turn it down."