The Boys in Green have a host of injury problems, made worse by Seamus Coleman's horrific injury after a horror challenge from Neil Taylor.
Defender John O'Shea has been allowed to return to Sunderland and it may present Egan a chance to make his debut.
Manager O'Neill said: "You don't want to give out caps just because they are there, you want them to earn it. But for experience, you would want that.
"Some players who have just come into the squad - like the two lads at Preston (Andy Boyle and Daryl Horgan) - have acquitted themselves very well in training and they are basically just starting out in their international careers.
"Some players who have been around the squad but haven't played regularly may well play as well, and whatever length of time they have on the pitch [against Iceland], it's a chance to try to impress, and that is what they will try to do.
"In all honesty and in fairness to clubs, some of the lads who played on Friday night who are still with us certainly won't start in the game and might not participate at all."