The play-offs in March will determine that when O'Neill insists he will take a break from his job as Stoke City manager to try and triumph away to Bosnia & Herzegovina in the semi-final to set up a decider against Slovakia or the Republic of Ireland.
A North v South contest, with so much at stake, might be a nightmare for a whole host of non-sporting reasons but in football terms O'Neill would be confident his men could deliver a dream outcome.
Who would doubt him? When O'Neill was appointed Northern Ireland boss on December 28, 2011 the team was in a mess. Results were bad enough but just as damaging was a disconnect between the fans and players, many of whom were questioning whether it was worth turning up.
O'Neill changed all that. With astute man management, superb preparation and clever tactics, he gave the players belief when they had none leading to improved performances and results.
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It took a little time though. O'Neill's first qualifying campaign as boss for the 2014 World Cup finals was a shocker and included embarrassing home draws and away defeats against Azerbaijan and Luxembourg.
There were chinks of light with a heroic 1-1 draw in Portugal and a 1-0 success over Fabio Capello's Russia at Windsor Park but even so the Irish FA had to be strong to keep the faith.
They were rewarded as Northern Ireland won their Euro 2016 qualifying group reaching the finals of a major tournament for the first time in three decades.
The 3-1 victory over Greece at Windsor, with captain marvel Steven Davis scoring twice and Josh Magennis also on target, to make it to the glamour stages will forever be one of the country's finest nights.
Many thought O'Neill's Northern Ireland would be one campaign wonders. Wrong. In the 2018 World Cup qualifiers his team performed maturely in their group to reach the play-offs where they cruelly lost out to Switzerland.
This time around O'Neill's players kicked off with four wins out of four versus Estonia and Belarus. It took the quality of Holland and Germany to beat them in Group C.
Missing key players in Frankfurt on Tuesday night, Northern Ireland went in front through Michael Smith's cracking strike before Serge Gnabry (3), Leon Goretzka (2) and Julian Brandt blasted the home team to top spot in the table.
The Dutch and Germans could win Euro 2020. The same goes for France, Belgium, England, Italy, Portugal and Spain.
Beating any of them is tough. Against any other nation in Europe, however, O'Neill's side are capable of victory which is why they can enter the play-offs without fear.
Skipper Davis is still a class act, the Jonny Evans/Craig Cathcart central defensive partnership is strong, Stuart Dallas is as versatile as he is consistent, Smith, Magennis and Corry Evans are reliable while younger players such as Paddy McNair, Bailey-Peacock-Farrell, Jamal Lewis, Jordan Jones and Gavin Whyte have blossomed in this campaign.
The qualifiers may be over but Northern Ireland aren't finished with Euro 2020. Neither is O'Neill. There could yet be a fairytale finish to his time as the country's manager.