To be fair to Garmin each iteration of their vectors have been different and the issues as far as I know are down to changes in design rather than power meter accuracy. I have vector 2 pedals and not having to use set tightening force was a big improvement over the originals. The current model did away with the pods that held the battery so in effect they are first generation of that design. That being said you would expect keeping the battery in place would be one of the simpler design objectives to meet when designing a pedal!
I wouldn’t expect any new model soon, not sure what Garmin would gain unless they were able to increase accuracy. The 3’s are ant+ and Bluetooth (one thing I wish my 2’s had was Bluetooth), no pod to break, loose, forget etc when travelling and if reliability is fixed I’m not sure what a version 4 would bring to the table.