Yes, I am excited to see how much on-chain usage can be reduced by multiparty channels and eltoo (if activated). Ark is an interesting idea, although Ark still has a pretty high onchain footprint the way I understand it depending on the frequency of coinjoin rounds (per Ark Service Provider).

I could see fees going to $500+ if Bitcoin were to have another 10x in adoption.

I've read about that issue with small transactions on lightning, but I don't think that it is too much of an issue because the attacker does not actually really get anything out of it, it just a grief they can perform. In lightning, node reputation is very important so it just seems like it would never make sense for the attacker. I'm not an expert though.