They have not committed to an engine. There is no engine commercially available to buy and no engine producer has committed to creating one.
For it to have a chance the US gov. needs to do IP transfer and pair them with NASA for test as they did with SpaceX, more realistically simply twist Pratt&Whitneys arm a bit...
That's not enough range to do London - Sydney, it's not enough to do Los Angeles to Sydney either, or Los Angeles to Tokyo, it's basically a replacement for trans-Atlantic flights only because even US cross-continental Mach 1.3 is only about 50% faster than a 737 (3h vs. 5h)... It's pretty much geared to the prestige market only.
Under an hour to anywhere on the planet, meanwhile, is absolutely someone would be a premium for -- and they'll do it for most/all long haul flights if it was available.
-Musk floats this vision since 2017. Why doesn't the company have a project to seriously develop it?
If I was to hazard a guess, the BFS concept is 2035 at the earliest, most likely 2040 -- and it'll be at a much smaller scale than previously advertised.
But as they say,"the devil is in the details"
- Can Starship transport people from London to Sydney safely economically, compared to Boom, which is working on a supersonic passenger aircraft ?
-Why can the boring machine dig tunnel at much lower cost than it's competitors? Maybe it's because the everyone else tries to dig tunnels for trains, which have a much larger diameter than Musk's boring machine, which only fits his "Teslas at a tunnel" concept? And it might be a good idea. Worth a try. But be honest about it.
-Sure, data centers in space probably have some great uses, and I'm happy he's trying, but will they ever be more economical than deploying servers on the ocean? On countries with very cool climate?, powered by new energy technologies?