Agree with much of what Noel Cleal says. Wane has done enough to at least see out the last year of his contract. Tony Smith is in no danger and there's no way Brian McDermott can get Leeds into a worse position than the ones from which they've won the last two titles, so he's safe too. Saints, Hudds, and London all have new (or nearly new) coaches, so I can't see any of them getting shut. Gentle seems to be well thought of at Hull, and Richard Agar's stock is well up at Wakey after a great first season, so they both go in the 'safe' column, for me. Betts keeps getting mentioned, but all the rhetoric coming out of Widnes for the last 12 months has been about slow but steady progress. I think he'd struggle to do any worse than last year, so I reckon he'll be fine.
Phil Vievers is in a slightly insecure position, I think. If Salford's new owners have a grand plan for the club, that might involve a clean start and a new coach. If that is the case, then even if they can't get rid of him straight away they'll be looking for an excuse to, and it being Salford one will come along soon enough.
Ian Millward had a dreadful first season at Cas, but it would be unfair to judge him on that, given the personal crisis he's had to deal with. Now that he's one season on and has made a few signings of his own, it'll be do or die time for him.
Craig Sandercock has had a disappointing first season, and has the disadvantage of being in charge of a club with expectations that might be deemed slightly unrealistic. He's my favourite to go first - if they aren't in solid contention for a playoff place by the halfway stage he'll be gone, I reckon.
Having said all that, I wouldn't be surprised if this ended up being the first(?) SL season in which no coach gets the boot. The absence of the threat of relegation makes it a distinct possibility; why spend lots of money paying off a coach when you can just wait for him to see out his contract?