What makes you think it's falling behind? None of these new tools compare to Principle imho. Principle is still the most powerful, and easiest to use prototyping tool. Most of these "new" features that Studio and Framer have been promoting, have been in Principle for years now. They're all playing catch-up. Just because something is new, doesn't make it better. And just because something is old, doesn't make it worse. I find that designers often follow trends too much, even when it comes to tools. Studio and Framer are the new shiny, hip things, so everyone is paying attention to them, but they're still not ready for primetime.
That doesn't mean Principle is perfect, there are definitely things that needs to be improve, but Principle integrated with Sketch is a powerful solution. In the end, just use what you like and works for you. Forget the trends and the fancy marketing campaigns.
What makes you think it's falling behind? None of these new tools compare to Principle imho. Principle is still the most powerful, and easiest to use prototyping tool. Most of these "new" features that Studio and Framer have been promoting, have been in Principle for years now. They're all playing catch-up. Just because something is new, doesn't make it better. And just because something is old, doesn't make it worse. I find that designers often follow trends too much, even when it comes to tools. Studio and Framer are the new shiny, hip things, so everyone is paying attention to them, but they're still not ready for primetime.
That doesn't mean Principle is perfect, there are definitely things that needs to be improve, but Principle integrated with Sketch is a powerful solution. In the end, just use what you like and works for you. Forget the trends and the fancy marketing campaigns.