I'm hoping that Lucis won't be the next step up from Ironworks, but rather an alternate progression for fishers who don't want to take the Ironworks path.

Getting an Ironworks rod takes an awful lot of work. If SE plans on continuing to advance to higher-level fishing with higher-level requirements, they're going to need to introduce alternate rods with less of a time investment.

Forcing players who wish to advance to get an Ironworks rod would be akin to forcing DoM and DoW who want to advance to acquire a Zodiac weapon.