Victory over Ireland in last weekend's quarter-final in Wellington has set up a semi-final final clash with France on Saturday and Ferris is convinced that a repeat performance will lead to place in the game's showpiece event on October 23.
"If Wales play like they did against us, there's no reason why they can't win the World Cup," said Ferris, who played alongside a number of the Welsh squad on the 2009 Lions tour of South Africa.
"They were very smart and took every opportunity. They have big, strong ball carriers and a magnificent back row.
"They've brought in a lot of young guys who have confidence and self-belief. They have the right blend of youth and experience. Fair play to them, they beat us."
Whereas Wales are preparing for their final-four encounter with the French in Auckland, Ferris and his Ireland team-mates have headed home empty handed.
But things could have been so different had the Irish kicked on after Keith Earls' first try leveled the scores at 10-apiece last weekend.
A strong start to the second half looked set to put Declan Kidney's men back in control but it was Wales who dominated the remainder of the match to end Ireland's World Cup dream.
"Wales played the better rugby and were smarter in the second half than we were," added Ferris.
"We felt like we'd played some good stuff in the first half. During half-time we regrouped and said let's get the next score. That's what happened, the game was 10-10 and we thought we were in the ascendancy, but then they scored that soft try.
"It's a team effort but we came up short. A couple of defensive errors and good teams like Wales will punish you."
While Ireland's World Cup campaign ended in disappointment, they did produce one of the results of the competition when they downed Tri Nations Champions Australia in their second pool match.
Ferris insists that triumph over the Wallabies has shown the squad what they are capable of achieving and the Ulster blindside believes it can act as a catalyst for progress in next year's RBS 6 Nations.
"It's gutting that we're going home. We felt we could stay out here another couple of weeks.
"We firmly believed that we could win this match and this competition. Unfortunately it hasn't happened. We'll take confidence from beating Australia, the Tri-Nations champions, and topping our group.
"We'll get another go at these boys in the Six Nations in a few months time. Hopefully we can turn it around then. This tournament's over so we must regroup and push on."