Proposal: Artificial Intelligence
Personally I would prefer mainly technical. It seems that a few of the questions involve semi philosophical, and somewhat subjective questions.
It should be both.
On a new site with technical questions only, most of the questions would be on-topic on the Data Science portal: https://datascience.stackexchange.com/
And I think with mostly theoretical questions the site would have not enough questions/visitors.
I also think it should be both. Here are other reasons to build on @Iter Ator's answer.
I think it would have to be only theological, and not technical. If it was technical, then a lot of questions would end up being duplicates of existing websites that already handle technical questions (such as "data science").
The philosophy about AI is remarkably separate from actual AI research/development, and it still remains that way because "artificial intelligence" is itself a philosophical concept, dealing with vague concepts such as, you know, the term 'intelligence'. The type of people who are interested in building AI are not necessarily going to be the same people who want to learn about AI and make predictions about the future. There's already lots of resources for the former. There's very little (informed) resources about the latter.
I don't worry about people getting bored asking about AI philosophy and leaving the website. AI is not going anywhere, and neither are disputes over the definition of 'artificial intelligence'. There will always be demand for somebody to ask and answer questions.