I was actually thinking if I should:
(1) stay with TK and aim for Elite+ and thus have 4 years to start over with a different program or continue with TK
(2) move to a more generous (?) UA
(3) move to Asiana to get their lifelong *A*G
(4) switch to LO/LH as I fly them most, try to earn *G status there
If you fly discounted economy you'll never make SEN, so (4) is a no.
Making (3) would be a big gamble, since you can't be sure OZ will keep the program running for the next 10 years. You should carefully compare the earnings on UA and TK according to your travel patterns. Since you actually fly a lot, UA might be a better choice for cheaper redemptions, but keep in mind that you wouldn't get domestic lounge access if you fly UA within the US!