Air Drop Booster

Last year after a Falcon launch, I mentioned that to replace stage one, any drop system must get to Match 8 at 40 miles up to replace the booster stage (as an air breather rather than being lox loaded).

An airdrop alternative would be done from a vehicle modeled after an SR-71 and the launched vehicle would have to include SRBs. They could either be rejected or sent to orbit with second stage, where both would stay, physics permitting, for use in construction of stations and interplanetary boosters. Nothing wasted. SpaceX may not like it, because it would displace Starship in some aspects - or maybe it might enhance it.

The more important factors are whether spinning stations are actually possible, given inner ear issues, and whether we can get hydrogen and oxygen to orbit for fuel via space elevator. See this for more information.