Do you think an ad-free, subscriber-supported newsletter covering developments in Artificial Intelligence would be sellable and sustainable?

You ask an interesting question. AI is a broad field. Are you planning to specialize or generalize your content? In a world where traditional subscription-based media struggles to stay afloat, you are choosing a risky option to deliver content.
I have been in magazine and book publishing for 30 years. Lots has changed in those decades. I have switched to online course creation as an alternative to traditional media. There is a strong trend toward online courses. It is possible to create a valuable newsletter for a target audience. Start by tightly defining your ideal subscriber. You must know who you are creating content for and why. You must be confident you can create highly relevant and useful content unavailable to access freely. What are the benefits to the reader? Use the Minimum Viable Product concept to begin your process. You don't want to invest any more than necessary for an unproven product launch. Consider using the Ask Method to help you determine the viability of the product. Marketing the product is like any other launch. You need visibility and authority. Guest blogging, and media coverage are recommended. Create a website or blog with detailed, authoritative content you can work to get high SERP rankings. Podcasting is another way to build an audience. Researching for audience interest and competitive analysis are also strongly recommended before you launch. Feel free to set up a time for a follow up call via Clarity.

The simple answer is yes. But, you'll have to compete with what I would say is the current leader in this space - Rob May's Inside AI. https://inside.com/ai

Rob is a leader in the space, he runs an AI business, and pulls together thought provoking articles and links. There is a free, ad-supported, version and a paid version.

The best way to start any newsletter is to just start. Then remember some key things:

1) Always be building your email list. You must own this part!
2) Grow your readership by also publishing in other places like Medium, LinkedIn, and other tech / AI pubs. Drive them back to your original site and get signups.
3) Promote everywhere and always on social media.

If you're hoping to remain ad-free, then you'll need to start with a free newsletter to grow membership. It acts as an onramp to the paid version as well. Plan out how you want to make the paid offering better. Does it include in-depth reports, unique interviews, survey results, video or webinar content, or..?

I read Rob's report every time. I'd check yours out as well. If it has an interesting stance- a take on the industry -then you'd keep me coming back, too.

My published posts average tens of thousands of views each week, and have been Top 20 posts on publications like Startups.co. If you want to grow your newsletter, I can help. Let's setup a call to follow-up.

Yes I believe it's possible, but it depends on whether your audience perceives if they will get value at a level which is worth more than whatever your sale price is.

Also, and I hope this is obvious, you need an actual audience of people interested enough in AI to financially invest in learning more about it.

My advice is 1) know exactly who you are going to sell this to, and
2) Create the first newsletter, publish it publicly and then promote it to see who from your audience signs up.

If you don't already have an audience you're going to need to build one.

Yes but focus on a niche or target audience. The AI space borders on a number of vertical industries as was technology areas (chatbots, Analytics, Autonomous Vehicles, Machine Learning, Smart Speakers, etc.) . It is also very misunderstood in its application to business problems. Build your competency where you have credibility from experience, access to resources and your network. There is a lot of noise out there that will prevent you from being heard so you have to target those that are overwhelmed or at the starting point and looking for clear link to their business objectives or technology roadmaps.