Enterprise failed and we're still here.
Four seasons and nearly a hundred episodes is a failure?
Less than two million viewers a week when it went off the air, a drastically slashed budget and the only reason it got the fourth-season was because they needed more episodes for syndication.
If it wasn't a 'Star Trek' series and on a mini-network, it would have been cancelled after season two. So yeah, from a numbers perspective, it was a failure. If CBS had it to do over, they likely wouldn't have made the fourth-season since there is no syndication market for it.