As I started to write this, there was only a picture on the Elektron site, but since then De:Bug Mag have posted a 9 minute video of the presentation by Cenk - the main Elektron product demonstrator, so you can ignore my speculation, or not...
No details, just a great big picture with a sticker saying effectively - wait till Tuesday.
What we can see is that the Analog Keys has a keyboard and a tag line which says - Four Voice Analog Synthesizer
Which kind of gives the game away somewhat. It has a 3 octave keyboard and a livery which is simillar to the Analog Four(see our video) and Octatrack with the signature Elektron eight rotary encoders, so we can expect a simillar OS and structure. If I had to guess - and I do have to guess (no inside info here folks) I'd say its a four-voice poly version of the Analog Four - but with out the complex sequencer, although there is a record, stop and play set of buttons. Perhaps rather than four individual voices its just a regular four voice poly.
I realize you can probably figure this out yourselves from a good squint at the photo, but if you don't have much on this weekend, you can stay in and speculate. Come Tuesday, we'll know more. I guess the big news is going to be the price, Elektron traditionally havent been about budget, but surely with the latest brace of affordable analog synths, there's got to be pressure to compete on price.