To me, that seems like a pretty reasonable approach... adding a password change at the end would probably be a good last add.

I tend to generate my passphrases for sites now, my only complaint is a password field should accept at least 100 characters. Assuming it's salted+hashed anyway, it's almost irresponsible to limit to under 20 characters. I'd rather see a minimum of 15 chars and a suggestion to use a "phrase or short sentence" in the hint/tip.

I wrote an auth system and integrated the zxcvbn strength check and HIBP as default enabled options. The password entry allowed for up to 1kb input, mostly as a practical limit. I also tend to prefer having auth separated from the apps, in that if auth fails via DDoS, etc, then already authenticated users aren't interrupted.