True enough. Apart from the two ways I mentioned, there may be the tachyon particle and quantum entanglement.
One has not been proven to exist yet and doesn't actually seem necessary to explain anything, and the other bars useful communication because of the inevitable observer effect triggering a spin change when all you're trying to do is check for incoming signals.
And other not-really-FTL phenomena as mentioned in your linked article, such as the movement of shadows and abstract points or sound waves in materials of absolute rigidity.
Other methods can't be ruled out, of course, but the least out-there methods would be warp drive and wormholes, and perhaps quantum entanglement as a means of communication (if the inherent difficulties of making the travel systems work can be overcome, it's no more unreasonable to imagine the observer effect being circumvented).
Tachyons for communication is not a good idea, as tachyons arrive
before they're transmitted. The longer the distance, the longer before they'll arrive.
I know we're in the business of sci-fi, and that means sometimes we just have to wave our hands vaguely around and step firmly into the realm of pseudoscience - it would be too restrictive otherwise. I just personally prefer to keep the use of 'handwavium' to the minimum amount necessary. :)
My intention with these elaborations are to tell the story, to the best of my ability, of what current physics predicts and what it does not predict.
And that's why true FTL and even near-light-velocity travel must be considered deeply impractical. Certainly, velocities of a significant fraction of C could be used; contrary to intuition, a trip made from Sol to Alpha Centauri at 75% of C wouldn't take just over 6 years for the travelers, as their local time slows down. It would seem significantly faster. From the viewpoint of Earth, though, it
would seem like just over 6 years. This leads to time travel into the future, and is usually not what you want from an interstellar travel method. It's not terribly bad when dealing with a nearby star and a relatively low fraction of C, but increase either the distance or the velocity, and the time discrepancy will make the running of a functioning interstellar 'empire' impossible with any degree of cohesion. Breaking through the 'light barrier' (although manifestly not an option, unless everything we think we know is wrong) would complicate matters even more by mimicking the tachyon and arriving before you depart; time travel into the past. A travel method that keeps everyone in roughly the same time frame is necessary for creating a story which doesn't feel to alien to us humans, even if that's not how the universe really behaves.
We need something which can make the round-trip to Alpha Centauri in, say, 8 hours
and arrive back at Earth 8 hours after departing, Earth-time as well as ship-time and Centauri-time.
It's always fun to throw some relativistic causality-violating stuff into a plot, but it's better if the general means of conveyance used doesn't produce paradoxes :)