Is 8GB adequate (M3 iMac) for the upcoming Apple Intelligence upgrade?

Apple Intelligence Preview - Apple

"* Apple Intelligence will be available in beta on all iPhone 16 models, iPhone 15 Pro, iPhone 15 Pro Max, and iPad and Mac with M1 and later, with Siri and device language set to U.S. English, as part of an iOS 18, iPadOS 18, and macOS Sequoia update this fall. English (Australia, Canada, New Zealand, South Africa, UK) language support available this December. Some features, additional platforms, and support for additional languages, like Chinese, English (India, Singapore), French, German, Italian, Japanese, Korean, Portuguese, Spanish, Vietnamese, and others, will be coming over the course of the next year."

It appears that 8 GB is enough to run Apple Intelligence – and is the cutoff point that determine which iPhones and iPads will be getting the beta, and which won't.

As to whether 8 GB is ideal for running Apple Intelligence, or if it would be better to have more RAM, Apple doesn't say.

No one knows for sure, however if you are considering a new iMac I would recommend 16-24 go.

Yes, fine.

It may be adequate but that does not ensure you will be happy with the performance. That goes for all 8GB Macs, regardless of whether or not they can run Apple Intelligence.

FWIW, Apple is expected to bump up the minimum RAM on new Macs to 16GB. So your question may be moot if you're asking about a new Mac.

Sooner or later you'l be quite unhappy with only 8 GB RAM.