The IRFU decided not to offer Kidney a new contract and he has left his job as coach ahead of the end of his current deal on June 30. Hickie, who also played for Leinster, has named Conor O'Shea, Mark McCall and Joe Schmidt as possible replacements for Kidney.
But Hickie believes it will not be easy to tempt the likes of Harlequins director of rugby O'Shea, Saracens director of rugby McCall or Leinster coach Schmidt, and said: "It will be a big challenge to see who they can get."
He added: "Mark McCall is doing a very good job at Saracens. Joe Schmidt, the Leinster coach, would be a great public favourite. It's whether they can get a guy like him to commit to Ireland for four to five years."
Ireland suffered a poor Six Nations campaign which featured shock defeats to Scotland and Italy and a fifth-placed finish which saw the country fall to a lowest ever world ranking of ninth. The loss in Italy on the final weekend of the campaign led many to call for Kidney's resignation, so Tuesday's announcement came as no surprise.
A statement from the IRFU read: "The decision was made following an in-depth review process carried out by the IRFU's National Team Review Group (NTRG). The IRFU thank Declan Kidney for the unquestionable commitment, passion, professionalism and success he has delivered to Irish Rugby to date.
"The IRFU, through the NTRG, will continue the process of identifying suitable candidates for the Ireland coaching role."
Hickie believes injuries played a significant part in Ireland's poor Six Nations showing, exposing a lack of strength in depth, as the 2009 champions came up short.
Ireland had to deal with a debilitating injury list which robbed them of key players such as Paul O'Connell, Jonathan Sexton and Simon Zebo.
"In recent years, certainly this year and even last year, there has been an horrific run of injuries," added Hickie. "When Ireland won the Grand Slam they used 21 players and this year they used 36 and Ireland doesn't have 36 front-line international players."
- Sports & Recreation
- Joe Schmidt
- Declan Kidney
- Mark McCall