The 3rd Servile war was the last major slave revolt until...maybe the Haitian slave revolt circa the French Revolution?*

Unfortunately, it's hard to draw any concrete lessons from the incident.

The 3rd Servile war happened just after Rome had gone from regional power to a Mediterranean-spanning empire. They'd recently won wars with a lot of other people and had come home with hundreds of thousands. So many slaves that it disrupted the economy. There were slaves everywhere and they were so cheap as to be disposable and so they were disposed of frequently. Rome had no laws protecting slaves. They were, legally, no different from a chair or a hairbrush. Obviously, this builds up resentment, so when Spartacus and company broke out of their gladiator school, they were the spark on a whole lot of tinder.

When the rebellion was put down, the Romans were indeed brutal, but at the same time, the Senate passed some laws ensuring at least some basic rights of slaves, which probably diffused some of the anger that had fueled the 3rd Servile war. Perhaps more importantly, conquering Carthage (and bringing home an unlimited number of slaves) wasn't something Rome could do every day. As the supply dried up, slaves already living in the Empire became more valuable and therefore better treated.

Given all those factors, it's difficult to say for sure what effect the crucifixions had on the slaves. The aristocracy, who wrote all existing accounts of the war, didn't raise any objections to the mass-executions.

It's maybe worth noting that the 1st and 2nd Servile uprisings were nowhere near as impressive as the third. They were localized affairs and hardly get any mention in most histories. They're mostly important to the Roman aristocracy of the time, who lived in constant terror of slave rebellions.

*: Surely not. Does someone have an example of a revolt that happened earlier?