There is no timeine or confirmed changes. This thread is purely speculation from surveys. CX hasn't confirmed any MPC changes yet. Only "real" change that's happening is the Boarding Group Trials, where SL boards with PEY (Group 3) instead of J (Group 2). GO Still boards with Group 2 (J) so I doubt there'd be any changes coming forward soon that impacts GO's value a lot, so I'd say you're safe booking with CX unless something in GO's perks mean a lot to you.