Many have tried to take a slice of FB’s pie - almost all failed to make a serious dent, and the main social media alternatives are also generally struggling (or have serious fundamental issues of their own).
At this point, I’m very skeptical another company will unseat FB’s dominance for quite a while, if ever.
That's true, but there's a difference between FB and Friendster/MySpace: Zuck is apparently trying (and succeeding) at managing that risk.
Instagram was growing quickly and could seed the next big FB competitor. So FB bought them for a $1B valuation almost everyone thought was crazy at the time.
WhatsApp could seed the next big FB competitor. So FB bought them for $20B or so, which again was mostly considered crazy at the time.
Neither of these is crazy in retrospect: FB's dominant position is easily worth what DB paid for these and more.
FB didn't manage to buy Snap, so they started waging war, adding Snap's features 3 times (to FB, WhatsApp and Instagram).
FB management is actively trying to stay dominant. MySpace was, in comparison, passive; and friendster was never as dominant.
Okay, then just wait and see what will kill Facebook, since you already described what killed previous networks.
I personally think what will kill Facebook is simply maturing internet and hence maturing people that use it. Most people (family) I had on Facebook deleted all their likes, and pages their follow, and artists they listening to; my brother told me "I have no idea why I added this dude guess I was young". Eventually I bet 30% of Facebook will wake up to privacy abuse FB made its business, and will move on.
Disclaimer: my view can be distorted, since I'm building a new social network.
Whatever kills Facebook won’t look like a social network - they will see and fight it.
It will look like something else but turn out to be a social network replacement in retrospect.
Microsoft was not dethroned by Linux or free software (cheaper and arguably better) - it was dethroned by mobile phones. And it’s still alive, just not the king anymore.
If you think solid $ numbers are everything to keep "printing money" then see what happened to Kodak or Sony.