Anything where you play buzzword bingo is not going to be lucrative in the long term. The technology's popularity attracts wannabes, which increase the supply of available labor, which drives down wages.

I'd go with something that requires specialized knowledge, either domain-based (bioinformatics, geology, finance), systems programming (compiler, OS, and distributed computing), or one of the AI subfields (information retrieval, machine learning, data mining, computer vision, etc.)