Currently they're using ultra-light titanium armor and 20hp, which means they can die very easily in even level 1-3 systems. Given it's quite possible for a fight to be happening around a gate as you enter a system, signs should be able to survive long enough to communicate their messages.
We can do this by scaling their stats by level so the same number of average hits are needed for a standard weapon at that level, have them repair themselves (or have ships come out to repair them), or just make them immune to damage.
Improving survivability would make them viable much later into the game, allowing more effective use of commonwealth travel warnings to flag important/dangerous areas.
Another thing that might be worth doing is looking into making it possible for players to interact with them via the comms menu if they so choose, rather than docking, or some other thing to replace or augment docking with them. Heck they could even yell at the player the first time they fly past or something.
...basically they're a very old system and reviewing how they work is probably about due.