One of the major problems with all the technical/scientific sites of SE was always the constant homework bombardment. This has always been the case for every programming community since the dawn of time. This causes major user friction, spawns rudeness in return and creates immense amounts of moderation work.
We even had a “homework” tag at SO initially, just so people could ignore such questions. Other communities like Programming and Electronics changed names to Software Engineering and Electrical Engineering in attempts to lower the noise question bombardment.
One easy solution to this problem would be to split technical/scientific communities into an open part where everyone can post, and a professional part where you are expected to know the basics in advance. It could either be a separate site per community, or something as simple as having a tag “professional” and then those who don’t want to wade through homework can add that tag to their search filters. Homework questions ending up in the wrong place could easily be moved to the right place by any user, creating a minimum of friction. And without the usual “elitist” debate, since everyone would be welcome to post whatever is allowed in the open part of the site.
This is something that SO has always severely lacked, so I believe the ability to swiftly move homework questions to where the sun doesn’t shine would attract experts to a site free of such questions. I’m guessing that many experts and people using SO in their line of work would abandon SO instantly for such a site - I know I would.
I believe one key to success for a new site platform is to offer a better programming community than SE. SO is without the flagship and cash cow of SE. What SO lacks though, is freedom from noise questions. There’s lots of programming sites with lower standards than SO out there, none nearly as successful. I therefore believe a new programming community must have higher quality standards.
If it is too early to speak of specific communities, it might still be worth keeping the “several sites with same topic” idea around during implementation of the platform itself.