Was intending to answer this:
How low do you think they would go?
Fair enough, I did ask that.
If it was 1 cent per channel, then that is almost a micropayment itself.
With channels, there is also the cost of the ECDSA signature verification. That could end up being expensive, if the micropayments are small enough.
Bandwidth costs also matter. Is sending the extra micropayment more expensive than verifying it and is that more expensive than the amount being sent.