In terms of Super League

Wigan - very likely - replacement for Sarginson - most likely to have/use marquee spot for him particularly if Williams is off
Hull FC - likely - massive overhaul - looking to throw cash at players - may try and release a few players to get him in
Hull KR - possible - McGuire connection - maybe offer a bit more cash but wouldn't get marquee there
Castleford - possible - Daryl Powell connection/Hardaker effect/doesn't have to move far
Huddersfield - possible but think they're likely to be blown out the water
Warrington - i'd say unlikely with their cap situation but you never know
Catalans - unlikely - think living overseas may be too far
Saints - unlikely - think they've better centres at the mo
Wakefield - Very unlikely - don't think they could afford
Salford - Very unlikely - definitely can't afford

Why are Leeds letting him go mid season when they are in a relegation fight?

Two possible reasons.
1. To immediately free up cap space for a major signing most likely a half back.
2. He is so far off the pace this season, and looks a shadow of the player he was, and simply will not be overly be missed

The first reason is the only one that makes sense in terms of early release. Being currently hopelessly out of sorts just means he's in the same boat as most of our squad. Doesn't stop a whole bunch of players getting picked.

Sensible from Leeds - he’s been abject and they can bring in someone to strengthen the squad, which is badly needed. Question is whether they will recruit poorly again and waste the chance.

Not sure if it's been talked about anywhere but are Leeds subsiding any of his wages for the rest of the season as an incentive for Gold Coast to take him early?