I dont think ireland would walk Samoa/Wales/Fiji or South Africa tbh.. Wales can beat em as proved a few times in recent years, SA can beat Ireland and then Samoa and Fiji can push Ireland close and even beat em.
From Wales' group I think it'll be pretty close tbh as everyone can beat everyone (exept mabey Nambia) hopefully with Wales getting 2nd in the group but we'll see..
As for Ireland Imo their fans have way too much confidence, its one thing being confident but they have a air of cockyness tbf, Ireland should get out of their group unless they have a scare from Italy which is very possible (just look at this years 6 Nations) Then the 1/4's is where they're challenge comes.. As i said above.. Personally best performance from Ireland will be Semi's, worst if they cock up against Italy is failing to get out of the pools.