Imagine the day when the Ontario Human Rights Commission rules on which skyline is best and SSP then instantly becomes redundant.
I tend to agree that this isn't so complicated overall, with most people navigating all of it just fine in everyday life, but there are edge cases where "accept whatever I identify as" fall down and they generate most of the legitimate debate. They tend to be less about pronouns and more about social boundaries and expectations of what's available to whom.
For example around here we had Jessica Yaniv who demanded that ladies be required to wax her penis and sued them when they refused. A wider objection tends to come from shelters for battered women which argue that self-identification should not be sufficient for their residents.
Another example is stuff for gay men which women tend to want to attend. This could include say a clinic for people who are high risk of HIV or are HIV positive, or a sex-positive environment for people who are mostly interested in male body parts.
Another one I encountered was somebody who self-identified as "Sir" (in place of "he"; if I remember correctly was a trans person although I could be wrong about that) and potentially sexually enjoyed the minor act of control over others and their submission. I don't feel that people are actually entitled to be called whatever they want by others; it should be subject to negotiation and reasonableness on both sides like anything else.