I expect this to be problematic for those crediting VA flights to non-VFF programs, since booking Flex no longer guarantees a higher booking code than Choice, and you may not be able to force a higher fare code (to ensure you earn status credits) when booking online, without engaging a travel agent.
This would be similar to issues crediting NZ to other *A, crediting CX/MH to other OW etc. caused by this sort of fare structure.
Other than that though, I feel this is probably overall a good change if it means Flex will no longer be ridiculously priced
