I dunno, you should keep watching your curation rewards, they should still be ticking up even though you are only mainly a commentator. I don't think there is a one-size-fits-all rule about when it is etiquette to self vote, but if you aren't writing posts, you are missing out on a share of the steem that more stupid people are happily taking.

It may be that HF20 includes a ban on self voting. I can see this shaping up to be a HF worthy issue. Essentially, the self voters will force those like you to self vote, or watch them get the steem instead. This is an unacceptable situation and I think it will need to be remedied.

However, the increased decay rate of voting may ameliorate this, as the self voters spend their voting power down to the 20s and lower, and your received votes will probably be relatively worth more. So the steemit devs did consider this and it was included in HF19, and may be sufficient a remedy. The honeymoon will be brief for self voters, I think.

So it could go two ways, I won't say with certainty which way it is going to go.