A few years ago I would have laughed in anyone's face at the mere mention of this. Sure, there were obvious reasons why it might have been beneficial for him to make the jump--not money wise, but the schedule, among other things, would have surely been tempting, but no way a healthy(ish) Rey was gonna depart the financially lucrative McVinnieLand during the height of his popularity.
However... Dudes all but washed up these days, and is -quite literally- on his last legs in WWE.
Should the divorce between Rey and WWE occur anytime soon, can you see him and Dixie coming to an agreement? I personally can. Rey's presence in TNA would help boost their much sought after awareness in the US, and vastly increase their standing in Mexico. Like, I'm not too sure if there's still a working relationship between TNA and AAA, but add ReyReyJr to that deal, and it would be happy days for all involved.