I think this is a brilliant decision, and I only wish that it could have been made many years ago. I've always thought that pairs skating would prevent the "natural performer" in Tiffany from completely shining through. To me, there's too many tough tricks to learn and too little room for expression and originality in pairs.
I think with a few years of hard training, Tiffany could be a totally brilliant dancer. Like already said, she has some of the best carriage and line that we've seen in any skater, a regal elegance, a rare classical flair and natural charm, and SO much musicality. Most importantly, Johnny and her were known for their speed and edging when they still skated together (despite all the problems they'd had with the pair elements)--much thanks to Irina Rodnina and her Russian school of stroking.
I think ice dance is THE way to go for Tiffany, she has all the things I seek in an ice dancer. She can work on improving what she's always been good at, without having to worry about falling on difficult throws and jumps all the time. Besides, ice dance is also a much longer lived career, injuries notwithstanding.
I really hope she can finally realize her potential this time.