If you ever get a chance, read “the education of Cyrus” by Xenophon. It is so good. The way he brought together so many cultures is amazing.

It’s not just about an empire for the Persians. (But Persia is pretty good branding, that’s all)

Yes the country is for ever Iran, for all iranians of different ethnicities. The connotation in tourists's mind about "Iran" has to change, were the country to be called Persia today, it would have the same negative sound to it like Iran (arguably) does for some today. Also, most people would be able to distinguish a nazi use of the term Aryan and it's original meaning so that's really not a problem with the name Iran

I know that you're not confusing this but as some others might: Persian language is of the Persian people (although there are many non-persian L2 speakers), it should rightfully still called that and should not be confused with the (settled at this point) debate about the name of the country as a whole