well, for some values of “very likely”. ;) I base it on extremophiles. Life exists in volcanic vents and freezing waters. So it seems possible that at least microbial life exists somewhere else in the universe. Either way, “is/has there been at least microbial life on Venus, Mars, or Jovian moons” seems like a solvable question in the next 100 years or so. The conditions for intelligent life seem much more narrow.