Even if all the above comes together, though, there are hoops that must be jumped through. If the Twins put Thome on trade waivers, every other team in baseball would have a chance to claim him before the Phillies. And it's likely somebody would, especially an American League team looking for a designated-hitter type.
However, since he has a no-trade clause, he could decline assignment to a team he didn't want to play for and become a free agent. If he did that, he'd forfeit the remainder of his contract, about $500,000, although ya gotta believe that wouldn't be an obstacle for a guy who has made about $140 million in his career.