Seriously. I'm not saying that Elon would move SpaceX - but Tweeting loudly about the possibility feels like an obvious, in-character tactic to pressure the FAA.
1) SpaceX invested a lot of money into its American launch sites. Abandoning them altogether would be a huge waste of money.
2) Good launch sites are surprisingly rare, especially because you need at least some infrastructure there. French Guyana is probably the only real competitor right now.
3) Given that SpaceX is bound by ITAR, I don't believe the US government would let them launch from outside US territory at all.
1) "Eventually maybe we'll finally let you launch something" launch sites are of limited actual value. And there's no need to abandon the sites where launch approvals are fast and reliable.
No, nothing here is any sort of sure thing. But when has "it ain't for sure yet" stopped Elon from spouting off on a subject that pushed his buttons? Especially if he might be able to stampede Congress into passing legislation on his behalf.
While Boca Chica isn't really close to the Equator, its disadvantage against a launch point exactly at the equator is approximately cosine of its latitude, which at 26 N is still quite merciful.
Being in the continental US, South Texas has some major advantages that offset this relatively small loss of efficiency during launch. Various factory sites, such as McGregor, are within reasonable trucking distance. Most of SpaceX employees are Americans and Americans are more willing to move around America than to move to the other side of the world.
Queensland could work, even though the moving costs would be high. Small atolls in the middle of the ocean would be very impractical, though. Even Kwajalein has weather that rusts everything in its path.
At the end of the day, the US government and Congress knows that it is caught in a new Space Race with China and that it is in American interests to make the launch licensing process more streamlined. Not just for SpaceX, but for all its future competitors.
