Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Former Scotland manager Alex McLeish believes there are numerous strong candidates to succeed Craig Levein as boss, including caretaker Billy Stark.
The Scottish Football Association sacked Levein last week after a miserable start to the World Cup 2014 qualifying campaign and Stark, the under-21 boss, will take charge of Wednesday's friendly in Luxembourg.
Joe Jordan, Gordon Strachan and Walter Smith, who was McLeish's predecessor as Scotland boss, have all been mentioned as the next manager, with the SFA to begin the hunt in earnest following the Luxembourg trip.
McLeish, who was speaking at a Positive Coaching Scotland seminar at Hampden Park, said: "We'd need a miracle to get to Brazil now but hopefully the next group of games is going to give us optimism for the following tournament (Euro 2016).
"There's plenty of good candidates to take us forward.
"Gordon fits the bill. People were saying I recommended Joe Jordan the other day, but I mentioned him in the same breath as Gordon.
"I don't know what Walter's feeling is on it, but these are all guys who have definitely got the stature to handle that job.
"I don't know if Billy wants the job. I'm sure if he was asked it would be a different story.
"I'm not so sure Billy would put himself forward for the job.
"But again another good candidate. I brought Billy into the international set-up, knowing what a great coach he was."
McLeish's personal preference is a return to club football after leaving Aston Villa.
"It's not something I'm actively pursuing," he added.
"I feel I've got unfinished business in club football and I still harbour the day-to-day involvement."
McLeish praised Levein for widening the search for talent and incorporating players not previously involved in the Scottish set-up.
The former Rangers and Birmingham boss also believes the playing pool is better than when he was in charge and that they must take some responsibility for Levein's departure.
"I do feel we've got some good talent in the squad and Craig has sown some good seeds for the next manager coming in," McLeish added.
"A lot of them (the players) were stating publicly that they could have done a lot better for Craig.
"If whoever that is can galvanise the players to raise their game a little bit I don't see why we can't start winning international games."
PCS is a cultural change programme designed to create a positive environment for young people in football by teaching them to appreciate the value of effort and learning. Join Scotland captain Darren Fletcher and show your support for the principles of the programme by signing up to the PCS Pledge at www.scottishfa.co.uk