Habitable by some life? Likely. Life had a nasty habit of appearing on Earth for the sake of just being there and still does, and would persist even if we were naturally (or unnaturally) extinguished. Of course, until we find life on Mars (which I believe is extrordinarily likely as polyextremophile bacterium) or somewhere else (Europa, or the sulfur volcanos of Io, Triton, Titan, etc.) we are not qualified to make many statements as to the habitability of a planet. As it is the "current" life limits for pressure, temperature, radiation, etc are not written in stone. Every time someone says that life beyond certain conditions is impossible, it has turned out wrong.
Habitable by humans? It's unlikely unless helped artifically. We have delveloped over billions of years to be symbiotic with our planet and it's life, especially bacteria. Billions of things had to happen in a specific order for us to be here. Otherwise the planet might be populated with intellegent turtles, crocs or even dinos had they not perished, or did they...
as it is, it is estimated that we only know between 1/2 and 1/5 of all of the animal species that ARE on Earth.
Habitable in general? Possibly. Stronger magnetic fields, sheilding moons, water, etc. Who knows. Maybe billions of things went right on a rock orbiting a contact binary... Hopefully, the James Webb Telescope will shed some light on "Earth" like planets.