I'm pretty sure Widdopp said he was sorted with the Dragons when these rumours first came up some time ago. I'd also suggest that if it comes down to money, Leeds wouldn't be anywhere near what NRL clubs could offer - the exchange rate is still not what it was and the tax-free loophole has gone, not to mention the NRL cap is going to increase rapidly and there is currently a shortage of top class halfbacks in the NRL meaning they're massively sought after, pushing their wages up. About the only thing a SL side could offer in return is length of contract, so I'd suggest if there's anything to this story its likely to be an older player on a long-term deal.
I'd say Gallen is a more likely bet if you're looking at 'top' players. Happy to be wrong if it is Widdopp, I just don't see it happening.