They won't shift position, they'll convince themselves that it is all for the best.
Kegbreath has diminished the significance of US servicemen's deaths. The press 'across the board' has apparently tried to 'make the president look bad' as they took it to Leavitout at a presser.
These continued acts and sentiments which bring the callousness and sheer incompetence will leave it's mark. I think ostensibly you are right but Trump rode on the peace ticket during his campaign and 13 months in, there are dead troops and that MAGA base is dwindling.
When the point comes that very few people in the US trust anything that he and his administration say, that will be the collapse.
I think there are sufficient disillusioned numbers of MAGA's that will become more and more cynical and more and more vociferous that sheer weight of public pressure will tell.
By it's own design, the administration is so self serving and incompetent, they are continually stumbling, they continually f*ck up and the point has come where American lives are being lost in a war they never voted for. The pushback will come from both sides. Rubio and Vance both rode on that same ticket. There is no MAGA Mk2 to fill the void and no one would be able or want to take the reigns of this toxicity and turn it around.