To be honest we have never really know Apples expectations on anything they have released as they only ever report that something has done as expected without any proper elaboration. As commenters we have our own impressions and we come here to share much like bloggers and journalists do the same in their own mediums.This is actually an incredibly important point. We don't know what Apple's expectations were. Bloggers and pundits (and people who post in enthusiast forums) can talk about their own expectations or hypothesize about Apple's expectations, but without knowing either what Apple's expectations were or the actual sales data, it's just a lot of hot air.
The iPhone X has been unusual due to it being a very different product to any previous iPhone. It hasn’t been aimed at the mainstream user like say an iPhone 6 was so it’s difficult to gage. It’s not a device you are going to see dozens of out and about because it’s priced so much higher than previous iPhones. I don’t think the buzz for new releases is quite what it used to be due to all iPhones being very capable of doing consumers need. With that in mind it may well have exceeded Apples expectations for its intended market but it was never going to dominate the market either. Without knowing what Apple actually expected, we can only guess and it’s fine to do that.