In that case, it is possible and feasible to create a third party business making and selling cheaper antenna systems for the Starlink customers.
As I've mentioned in my other comments, I suspect the decreased in manufacturing for the antenna price is not so much due to the SpaceX better manufacturing iterations, increase yield, etc but mainly due to the recent availability of the high speed Direct RF sampling transceivers that now encroaching Ku-band territory.
Amazon claim they'll be able to hit $400. In Ka band
SpaceX spent $2.4 billion on dish R&D and production of 1 million antennas upfront with ST Micro. That kind of commitment goes a long way.
It's probably not. SpaceX doesn't have a separate modem. It's in the dish. These two companies got in via the military. OneWeb is in Ku band like starlink, they may be open to talk
Ka-band is still very high for the Direct RF sampling transceivers, if Amazon's claim is true then it's mighty impressive.
$2.4 billion is a lot of money to spent on antenna design and development, and if they don't have separate modem that explains the astronomical cost due to down/up conversion and perhaps most of the beam steering signal processing are done inside the antenna systems.
If the Starlink antenna has any patent applications, it will be very interesting to see their architecture. I think Direct RF sampling transceivers can make for much cheaper Starlink at least in the Ku-band antenna if their price are becoming cheaper themselves.
Based on this thesis (2021) that proposed a lower cost antenna systems for mobile terminals, Starlink has separate TX-Rx architecture that make their antenna system rather expensive [1].
"The limited operational bandwidth of the radiating elements integrated in their low-profile alternatives (i.e. slotted waveguide antenna arrays) actually obliges to split transmission (Tx) and reception (Rx) in two different panels, keeping a relatively high cost for the end-users."
There's a Reddit discussion on the ST developed antenna systems from 3 years ago [2].
There's also a teardown video of the Starlink antenna systems by Kenneth Keiter [3].
[1] Innovative 3-D printed Ku- and Ka- band antenna solutions targeting cost effective satellite on the move and 5G phased arrays
$150,000 is probably the cheapest in it's category