The only announced change to the 772 fleet is the reconfiguration of the 12F G-YMM* aircraft to 3-class aircraft starting later this year. These aircraft will presumably be refurbished at the same time as their conversion from 4-class to 3-class.
This will leave the existing 3-class aircraft and four 14F G-VII* aircraft that will not have received the new WTP/WT products and Thales (or perhaps Panasonic) IFE throughout.
In short though, your 3-class BKK flight will be the old WTP cabin, with the old Rockwell Collins IFE.