I thought I would be fine the with 50 Esteemed Elder cap, because it would give me a sense of completion. I'd have 50, and then I wouldn't have to worry too much about my Villagers' skills. I could just leave them alone for the most part and watch the village grow. However, when I actually reached 50 I felt deflated.

I'm going to miss making Esteemed Elders, so now I would like to know about this Island Event. Is it a random Island Event that pops up making a random Villagers an Esteemed Elder, or does have to do with ringing the gong? Thanks in advance!

There is an Island Event that can produce another elder, but it's not a likely scenario. You would have to get that specific event (out of the dozens of possible events), and a living Esteemed Elder would have to be the 'target' for the event. You can read about the event here.