New companions can be printed to mitigate Lurrus domination without introducing power creep. To see this, imagine they print a companion that is a Relic of Progenitus or Nihil Spellbomb on a beating stick. Now running Lurrus and all those baubles (instead of Mentor or Tinker) might become a bit of a glass cannon gambit.
Or the companion could be a bear with an ETB “gain control of target legendary permanent” effect, or a “moon” bear with a static effect like “all legendary permanents are Mountains”.
With enough hatebear companions, I could envision an interesting meta where a highly defensive deck with multiple companions in the sideboard (anti-blue companion, anti-graveyard companion, anti-workshops companion) becomes viable. This could open up the deck building design space, and increase the pool of vintage viable cards (just like Lurrus brought back previously unused cards like baubles and Dead Weight).