It's no longer in their hands. First of all they need to win against Northern Ireland tonight. Any other result will end their hopes of avoiding the last pot. Then they face an anxious wait, as they need Iceland, Faroe Islands and Luxembourg to stumble.
Of course, it's quite likely FAW know nothing about it so there won't be any anxious wait, just an unpleasant surprise when FIFA announce the seeding.
Matches involving Iceland, Faroe Islands and Luxembourg:
03 Jun Luxembourg - Hungary (Friendly)
03 Jun Faroe Islands - Slovenia (Continental Qualifier)
04 Jun Iceland - Denmark (Continental Qualifier)
07 Jun Faroe Islands - Estonia (Continental Qualifier)
07 Jun Belarus - Luxembourg (Continental Qualifier)
What results do the Welsh need, besides a win against Northern Ireland?
Belarus - Luxembourg 1 or (Luxembourg - Hungary X2 and Belarus - Luxembourg X)
Faroe Islands - Slovenia X2 and Faroe Islands - Estonia X2
Iceland - Denmark 2