I can't imagine why someone would want to do this. If anything, you're going from the best state for premeds to the worst state for premeds.
The number of medical schools in Texas and the closed nature of TMDSAS means that you are facing a much smaller competitive pool relative to AMCAS and AACOMAS. TX schools, to my knowledge, are also much less costly paths to the MD than OOS schools.
Conversely, CA has several esteemed medical schools that view themselves primarily as national resources due to their relative strength as institutions compared to flagship schools in many other states, so there is fierce competition, not only from CA students who would like to stay there, but also from students all across the country that would love to live and train there.
Even if you could change your residency status mid-cycle, I can only see downsides. If you plan on applying TMDSAS, it will probably cause downstream problems there. If you don't, I suspect you'll probably be considered a TX resident anyway (and thus assumed to be applying TMDSAS by OOS schools), where you'll probably experience some bias as well. There's a reason why TX students only apply to AMCAS for a handful of strong mission-fit schools they hope will overcome that bias.
In other words, this seems like the worst of both worlds.
