I don't have any insights on what the team plans to do with this. Yes, the current change is minor, but may already stop those using 3rd party scripts. I'm not sure if real user logging is going to happen. I'd guess that this is more towards setting up some rate limiting, which would probably help already. I completely agree, a blacklist approach likely won't work, it brings a maintenance nightmare and new accounts are easily set up. Not sure on the captcha approach - wouldn't this void all decentralization aspects? I'm confident the team will find a good compromise for all.
I think some anti-bot tools could be tweaked to work offline too, via temporary information read from/via blockchain. Either way, decentralizing anti-cheating on STEEM can be a hard to do thing. Maybe it would be something to address (if not already done) on SMT's.