I don't think we'll need incentive to vote for comments. People already vote for them at a cost to curation rewards

I think this is true to an extent, but today people vote on blogs posts much more often than they vote on comments. Compare that to the trending reddit posts where it's very common to see comments that have almost as many or as many votes as the post itself.

so those comments that do get votes would get maybe 38 times what they get now while most people will still get 0

While it will be significantly higher, I don't think it will be 38X for a few reasons:

• The distribution curve is changing
• People's voting habits will likely change in some way
• There will be a greater incentive to engage with posts by commenting, which should result in more comments. That means more competition for the comment reward pool.