TL;DR: 🚩🚩🚩🚩🚩🚩🚩🚩🚩🚩🚩🚩
Sure, this affects medium/large/Enterprise folks (that's where I was using Director -- though currently retired, so no existing self-interest in this email).
This will also affect *any* installation with a whopping two dovecot servers with mdbox backends talking to a single linux NFS server as well. That's not exactly "Enterprise". Replication is great, but it is not a replacement for Director (nor is any sort of load balancing, regardless of the confused comments in this thread about nginx).
I think the real issue here is that Dovecot is removing existing, long-standing, critical functionality from the open source version. That is a huge, huge red flag.
I'm also a little bewildered by the comment "Director never worked especially well". Worked great for me, at scale, for years. Complex? Yup, but that was the price of mdbox (worth it). And if you're setting up a proxy cluster (instead of a full Director cluster) in front of your IMAP servers, you've already tackled 90% of the complexity anyway (i.e. using Director isn't the hard part).
This *feels" to me like a parent company looking to remove features from the open source version in order to add feature differentiation to the paid version.
I've loved the Dovecot project for over a decade and a half. And incidentally I have a very warm spot in my heart for Timo and Aki, thanks to Dovecot and especially this mailing list.
I've also loved the PowerDNS project for a decade and a half, so this removal of existing functionality is doubly worrisome. I'd like both projects to be monetisable and profitable enough to their parent so that they continue on for a very, very long time.
But removing long-standing features is a bad look. Please reconsider this decision.