You might want to sit down first .. .
If we can assume - and we shouldn't - that Ireland will beat Cyprus, Israel will beat the Faroe Islands and France will beat Cyprus, then, with only the results between Switzerland v France and Ireland v Switzerland outstanding, the points' totals of the contenders in Group Four would look like this:
P Pts
France 9 19
Israel 10 18
Switzerland 8 16
Ireland 9 16
Ireland, therefore, would have to beat Switzerland on October 12th to have a chance of finishing in the top two in the group (a draw or worse would leave them behind France and Israel), a win that would leave the points' totals like this (with just the result of Switzerland v France outstanding):
P Pts France 9 19
Ireland 10 19
Israel 10 18
Switzerland 9 16
Assuming, then, that Ireland beat Switzerland on October 12th, if the Swiss had failed to beat France the Saturday before then Ireland would finish second in the group.
If, however, Switzerland had beaten France there would then be a three-way tie at the top of the table, with Ireland, France and Switzerland all finishing on 19 points.
Using FIFA's first criteria to separate teams level on points - "ranking shall be determined (by) the greater number of points obtained in the group matches between the teams concerned" - the mini-table would look like this:
P Pts France 4 5
Ireland 4 5
Switzerland 4 5
At this point the next FIFA criteria - "goal difference resulting from the group matches between the teams concerned" - would come in to play. So far . . .
Switzerland 1, Ireland 1; France 0, Ireland 0; France 0, Switzerland 0; Ireland 0, France 1 - leaving the goal difference table, with Switzerland v France and Ireland v Switzerland still to come, like this:
P F A GD
France 3 1 0 +1
Switzerland 2 1 1 0
Ireland 3 1 2 -1
Again, for the teams to finish level on 19 points Switzerland would have to beat France and Ireland would have to beat Switzerland, so the margin of victories in those games would determine which teams would finish in the top two positions on goal difference.
If that criteria couldn't separate the teams, it would then go down to the "greater number of goals scored in the group matches between the teams concerned".
After that the overall goal difference in the group would be the deciding factor, followed by the number of goals scored.
Remember, if just two teams finish level on points at the top of the group then the results between those teams would determine the order of their placings. In such an event, France would finish ahead of Ireland having won at Lansdowne Road.
CAN IRELAND STILL
WIN THE GROUP?
Yes.
Perhaps the most realistic hope of winning the group is on goal difference, in the event of Ireland, France and Switzerland all finishing on 19 points. In such a scenario Ireland would need to beat Switzerland by more than Switzerland beat France.
If the three teams finished level on goal difference and goals scored in the matches between them, it would all go down to the overall goal difference in the group. A sizeable win over Cyprus or, less realistically, over Switzerland, could give Ireland the advantage over the other two.
The only other hope of Ireland topping the group would be if they took six points from their last two games, finishing ahead of France on points (meaning the French would have to fail to beat Cyprus and Switzerland), and no worse than level with Switzerland.
In such a case Ireland would take top spot in the group having beaten Switzerland in Dublin, thus bettering them in the head-to-heads between the teams (the first criteria used to separate teams level on points).