Let's answer some burning questions.
1. HFI is supposed to be the new damage ceiling, but currently my best with her is 13.6M at S0, while HoO does 12.8M (equivalent time) or 14.1M (+2s). Saying the +2s isn't countable is pure dumb because 1.3M damage in 2 seconds outside of HTR debuff is amazing, whereas HFI is done after 13.6M with nothing to spare. Of course, these are just current knowledge. Also - note that the biggest advantage of HFI team is the massively reduced Ult cost for HTR, as you're going to need the full 125 SP on HoO DPS team. So no, HFI is not weak, damage is not everything - you're not doing any damage when you have no SP to Ult.
2. The next lightning support that replaces Eden will greatly improve this as well, as we know Eden eats into buff time and currently doesn't buff realistically all that much.
3. HoO's main DPS rank is at S2, which I have already explained in description. It is a massive upgrade over this, and costs only 50 pulls worst case (no valk pulled).
4. There are currently no other S0 DPS in this damage range. Prior DPS teams at S0 typically sit within the 11-12M range, and most of them incur 2nd support's field time. 7T does not deal near this level of damage, but it is insanely efficient due to HoT's mechanics. It is unclear how they would match up in real practice, because most of the places where you would use 7T are for weathers that already benefit her (she has insane bonus against Mech types too). But in other words, this also means that if you don't already have 7T, it's no longer an important upgrade.
5. HoO, however, does not paralyze like HoT/7T. This is likely the biggest challenge we'll face.
6. Of course, this is not even live yet, so who knows if these numbers would make it?