Webfonts, in theory, are great. Using them responsibly though, without negative impact on the user experience, is an engineering nightmare at best, impossible at worst.
Frederic Marx lays out his thoughts on web fonts vs. system fonts in a beautiful essay and concludes:
Sustainable product design is about forming a relationship with our audience over time. Users will appreciate our efforts to make them more comfortable if they come in the right dose at the right moment.
This is why I think webfonts will last.