I see zero competitors that offer anywhere near the revenue that YouTube offers. Until you have another platform that can offer anywhere near this level of revenue for content producers, there will only be YouTube. (Twitch is a different market and doesn't compete with non-streamed YouTube content, which I think we'd both agree on)
For that matter, perhaps it's a good opportunity to regulate YouTube's monetization policies, so that other companies can compete for content producers more evenly.