VAR is not going to go anywhere, so for me there are 3 things that could be implemented immediately that would vastly improve both the operation and public confidence in VAR;
1. Full transmission of sound/dialogue between refs and VAR control. This is single-handedly the easiest move to increase transparency, increase accountability and increase correct decisions made.
2. Remove 'clear and obvious'. I assume this is used as a way of letting refs retain some on-field power and to assuage some critics that the game is going to be run by video etc. Get over this ego driven policy and just make VAR call what it thinks is right and wrong, with zero influence from the prior decision.
3. Have a clear policy on consistency. At the moment even the bloke in the pub can recall a decision from only one weekend previous where the exact same offence has been treated completely differently (in some cases to the level of red card or goal/no goal). These ridiculous inconsistencies can smoothed out quickly and where the decision does need to be awarded differently, it is explained via point 1.
i dont see any of these as changing any rule of the game etc, just quick fixes to improve the process.