I haven't done the math, but it seems like Starship is potentially an incredibly cheap heavy lift rocket even in total or partial expendable modes, e.g if SpaceX fails to realize their full reusability goals. At this point, I think BO and others are only falling further behind.
We aren't really sure exactly how far along a lot of their projects are other than "not really close".
So, IMO, you don't need to invoke Starship to illustrate the width of the current gap between SpaceX and a company like BO that has never flown substantial hardware in orbit or beyond, on their own launch vehicle or otherwise. When they do start delivering spaceflight systems, we can re-evaluate the competitive landscape. New Glenn could absolutely put some real pressure on Falcon 9, if they can deliver it before Starship eats its lunch.
I don't think any place on earth is a good spot to build when playing with geologic timescales.
> A number of later studies have concluded that a global sea level rise of 200 to 270 cm (6.6 to 8.9 ft) this century is "physically plausible".[8][2][9]
Just probably not in our lifetimes. The maximum sea level rise will be hundreds, even thousands of years from now. In the absolute worst case scenario where all the ice melted, sea level would rise 230 feet. If we did nothing at all about climate change and kept burning fossil fuels until we ran out, that's actually a likely outcome. It has happened in the past when the earth was much warmer. It won't happen to us, because we're taking action. The final sea level rise would depend how we do with actively removing CO2 from the atmosphere, as it will keep rising long after we stop using fossil fuels.
7 feet by the end of this century is not impossible, but not in the conservative estimate. So far we've been tracking the aggressive estimates, not conservative ones.
The construction of a massive space port in one of the more desolate places in America is a pretty damn good starting point. Doesn't take a magician to round that out with an airport, hotels, convention centers, restaurants, etc. I believe there is already an uptick in real estate on South Padre Island and talks about some bridge to better connect the island.