Switzerland shouldn't have much problem with Northern Ireland. Better players, and looked really good in big/hard matches. I really like them and few of their players are my favorites after watching them in Bundesliga, Nico Elvedi is especially good so I hope he has great tournament. Croatia is obviously favorites against Greece but their playstyle doesn't really contribute us, we should probably give them more posession but block options so we can intercept ball and finally get space on wings. They really play slow football and don't have much quality aside from defence. Italy-Sweden is best game of playoffs and would be huge slap to Italian FA if they don't qualify, Sweden really doesn't have luck in this draws. Denmark should absolutely pass. They played real quality football last few matches so I think they should pass it easily.
The knockout round between 8 sides for a spot in WC 2018 will be next months, however, it as already been revealed who would play who.
Northern Ireland vs Switzerland
Croatia vs Greece
Sweden vs Italy
Denmark vs Republic of Ireland
Northern Ireland, Croatia, Sweden and Denmark will play their first game at home and the second away. All games will take place between November 9 to 14.
Here are the team I expect to go trough:
Switzerland
Croatia
Italy
Denmark (but it will still be the most open game in my opinion.)