I believe BitTorrent is still viable with the quantity of file sharing protocols on the Internet today. Competition isn't a bad thing and it comes in all forms. I believe there are still plenty of people who depend on BitTorrent for their services, regardless of other options. Some people like to stick with what the deem dependable.
If the files being exchanged are ones that it is deemed acceptable to exchange, then BitTorrent functions as well as it ever did. It's not a useless service merely because people are cracking down on illegal use of it, that's not the fault of the service. It's absolutely still viable.
BitTorrent, by nature, is designed to circumvent protocol. The people behind it are technologically capable of continuing to keep it relevant in the same manner in which they were able to implement its widespread use to begin with. They simply upgrade the platform, much like software or operating systems designers consistently update their creations, to continue circumnavigating internet protocols.
BitTorrent is still viable, even though there are a lot of other file sharing websites and protocols around now. File sharing is not going away and even if they shut down some sites such as isohunt or others, they will still find a way to make it work. BitTorrent is still viable.
Bit torrent is still very viable today even with extra protocols in place. However you are taking a larger risk then ever before. Many people still use bit torrent and will continue to do so until it is either completely shut down or people are truly arrested for using it.