Is it possible to create a plugin that will redirect a channel or track to an outside application? The DAW I am using is ProTools.
Technically it is perfectly possible. The question is, where do you want to send the data?
The most obvious one is just write it to disk using a AudioFormatWriter::ThreadedWriter.
Usually your host occupies the audio device, but if you have more than one audio device, you could open an other AudioIODevice in the plugin and write the data there (but be aware, that this is not the intended use, so there might be edge cases and unexpected problems). You need a FIFO here as well, since the audio devices run on different threads, and might even have different sample rates.
There are currently no ready to use streaming classes in JUCE (afaik), but people on the forum reported to have their own implementations for that purpose.
Can you tell a bit more about your use case, and where you want to send the data?