What ever became of the erlang branch?

https://github.com/couchapp/couchapp/tree/erlang

I never really understood what the main driver behind that was. Are there still plans to release that?

I like the minimalistic drive, but in the end it boils down to javascript on the serverside. Which you can agree with or not.

what would you want?

I don't think CouchApp is a good choice for any target market. Most people eventually need to execute more arbitrary code on the serverside. Theoretically the Wordpress crowd would be a good target, but they don't like to code. You would need to aim for zero configuration. (it's fine, just know your market) Personally, I wouldn't feel safe to rely on CouchApp. What if my site goes viral and I need much more functionality? I'd have nothing to build up on, and I'd eventually need to rebuild on nodejs or something else.

A Couchapp has features that are trivial in couchdb (replication, map-reduce) but require more setup in traditional server side code. The target market will be applications that value these tradeoffs.

If you decide you need something else, I don't see the problem with having some parts of the application served by couchdb and some served by node. Put it behind varnish, cdn the static content, add a queueing system or whatever...

I think a couchapp is a decent way to prototype something out and if it goes viral you're going to be rewriting everything anyway no matter what system you use.