I have a trip coming up in early March to BKK.

IAH-LAX-NRT-BKK Then BKK-NRT-SFO-IAH. Segments in bold are not able to apply my GPU's to due to fare class(K).

(1)Will this change as the flight gets closer?

(2)Can I purchase an upgrade to a higher class keeping the same itinerary that would allow me to apply the GPU's?

(3)If I can would it even be worth it on these legs in the hopes of getting the upgrade?

Any advice would be greatly appreciated.