It really depends on what you mean by "viable", and I'm not trying to be flippant about that. Bitcoin could shoot up tremendously with another bull-run or a significant use-case; when this happens all of those coins you mined in the past will become a lot more "worth it". You can mine at a loss today, but as long as you hold onto your BTC you can make the decision when it is the time to cash-out or not.

The short answer would be yes, although if you're looking to profit at today's prices then the search becomes a little harder. Still entirely doable though.