You are correct about your concern, the LED in the optocouplers does degrade over time.
Since a Triac, once that it latches, does not require additional triggering...................Something that you could do, is not to have the optocoupler on continuously, but pulsed.
In a 50 Hz powerline, each semicycle lasts 10 msecs. In an inductive load the current will lag, very worst case 90 degrees or 5 msecs after the voltage zero crosses. But most likely the current lag will be between 2 or 3 msecs after voltage zero cross.
So synchronize a delay with the voltage zero crossing, wait for 2 msecs, and then apply a 3 msec pulse. Then the Led will be on for just 3/10 = 30% of the total period.
The complete circuit can be done with half LM393 comparator, and the two monostables contained in a single CD4538.