GS Music doesn't seem to be on the list for Super Booth, but I'd love to hear about a new synth from the makers of the GS Music 7. The GS Music 7 is an analogue synth with two digital effects and sounds quite Oberheim-y to me. It's around £1,600. It sounds beautiful but is the wrong beautiful for me right now. But I'll be keeping an eye out for whatever they do next.
Supercritical are in development of an six voice analog polysynth - albeit with digital control (so DCOs, etc.) - called the Redshift 6. There hasn't been much audio shared yet, but it looks a bit different and could turn out to be good. This is available for pre-order at £1,098.
I would really love to see a Korg Prologue Desktop (with either eight or sixteen voices); but as they have deprecated the Prologue and just released a lot of new products, I don't think that will be happening.
Pittsburgh Modular are going to announce a new synth, but I don't know what it is and I doubt that it will be poly. It could be their new Voltage Research Laboratory which is definitely quite a long way along in developement. They are also hoping to bring out a drum machine either at the end of this year, or the beginning of next. Both of those products are sure to have analogue signal paths. Pittsburgh Modular and Cre8 Audio, with whom they collaborate on production runs, are both going to be there.
Erica Synths might have an update or even a release for their monophonic physical modelling synthesiser. I think that is fully digital, despite being focused on aeorophone sounds, which I think could potentially have some analogue stages.
Otherwise I don't know what to expect. I've heard that there are rumours (that's right, I hear a rumour that there were rumours - not the rumours themselves) that a twelve-voiced version of the Polybrute could be in development and Arturia will be at Superbooth; but I think that it is two close to their last release for them to have something else ready to go; and they wouldn't want to hurt sales of the six-voiced version.