A new SIGHASH scheme is currently being discussed, called SIGHASH2, it is said to have more flexibility without introducing much complexity and it solves a few minor issues with BIP143.

Some of the new hashtype definitions are signing fees to make sure they are correct without signing some inputs, decoupling INPUT and SEQUENCE to have a NOINPUT option with a relative lock-time, signing INPUTINDEX, putting NOVERSION, for enforcing BIP68, and NOSCRIPTCODE, in case the public key is being reused, in the second byte some reserved bits for the future and lastly sigversion to avoid any conflict between past SIGHASH schemes and any future ones.