While not quite the same value, a Resilience value, or R stat, does about the same thing. A Land Raider might be 5 R, or maybe even 6 R. A Spartan would certainly be 6, for example.
Lasguns would need to hit and then wound five total times to inflict a single armor save against any vehicle with 5 R, for example. So, that 30 Guardsmen wall would need 30 hits, and 30 wounds to force six (6) armor saves. With AP0, or AP-, at that point, too.
So, AV is unlikely to ever come back; the R stat might work in a pinch.
1 - Guard
2 - Astartes
3 - Land Speeder
4 - Rhino, Dreadnought
5 - Land Raider, Venerable(?) Leviathan Dreadnought
6 - Spartan, Fellblade
+ - ?
The clear issue would be the full rework of other values, such as 14 point, 2 W, 2 R, 4 T Astartes, 4 point Guard as is, etc.