I think a line of "full-sized" versions of the Refaces is more interesting than an extension of a line of mini instruments.
Mind, I do love my Reface DX. Love the sound and the interface, but I'm not tempted to buy another Reface.
Although I think the CP and YC sound very good, minikeys aren't the way to play such performance instruments in my opinion.

As for the CS, I have 2 PLG150-AN's in my CS6x and I really like to see a decent instrument with all the interesting features that the PLG/AN1x has, such as free EG.
I think the sound of the AN engine still is amazing, but in the Reface CS too much nice features and possibilities are taken out to be interesting for me.
A reface CS80 would be very nice by the way.

I think a VL and RX could be a nice addition to the Reface line of products.
As for a SK, Arturia has the Solina soft synth and Waldorf the Streichfett. The latter is pretty good in my opinion and nicely priced.

On the other hand, there is some competition on the moment when it comes to minikeys instruments in this price segment.
Korg has his Volca's and Roland the Boutique line.
I think the boutiques are pretty impressive.
When it comes to sound I think the Boutiques take the cake.
I really love my JP-08.
The Reface undoubtedly has better keys. The Boutique keys are ok (much better than the Korg minikeys on the MicroKorg and MS20 controller), but Reface has the best minikeys I had my hands on.

So in the end I am not reluctant to new refaces, but what I really like to see is a new innovative instrument or an further developed version of an instrument like the AN1x or FS1r.

I would second the reface SK as I always loved string machines.

But my real desire would be for a Reface TR -a mellotron/Chamberlain but it would be need to go from F-F or G-G instead of C-C like the other reface instruments. Add AR envelopes, a looping option, reverb and phaser and it would be nirvana. One thing though to add would be the ability to download your own sample sets.

I am probably a minority but I like the small form factor of the reface series. As an owner of both a reface DX and YC I really like the apparent limitation of having a keyboard do only one thing but doing it well. As a guitarist about a decade ago I had multi effect units but now I just have a limited number of pedals but the ones I own do their function well. This prevents option overload.

As far as the roland boutique is concerned I would have loved those if they got the polyphony right. Four voices is just too little. The eight in the jupiter8 was for 8 voice polyphony like the 6 in the Juno 6 was 6 voice polyphony.

For current line Reface synthesizers the best addition IMO would be reface style RX rythm machine.

I use now YAMAHA S90ES drum&percussion presets with Reface YC. But great studio 22kg piano-synthesizer with small lovely mobile keyboard.. 🙂

How about reface YAMAHA CX5M to complete studiio setup? ))

Reface CSII

Velocity assign switch: Assign, Play, Clear. Moving the switch to the momentary assign location assigns velocity to the next sliders that are moved, with polarity determined by direction. When released, the slider snaps back to Play. Move to Clear to remove all velocity settings. This is my number one request. You could also implement an LFO assign switch in the same manner and that would provide multiple destinations.

Add a sawtooth + pulse + triangle wave type. Use texture mod to crossfade and pwm.

Add a detune slider in the osc section with up to an octave shift. This would free up texture/mod to do other things.

Add reverb effect type and/or reverb/delay.

Make the carrier completely cut out if mod is maxed out in FM mode. Else add a dedicated noise setting in the osc type.

Add LFO waveform slider with sine, tri, square, saw, s/h, noise. (Pay attention to polarity: saw and square should not be bipolar.)

Include a master tune knob on the back of the unit. +/- 100 cents. This is my second highest request.

Replace midi dongle port with real midi din ports.

Include 1/8" headphone jack at front.

Silk screen the power up key mode legend above or below the keyboard. Include the ability to set midi channel on power up. Add an option to switch portamento to glissando. Exponential envelopes, option to turn the looper into an arp, different filter modes, etc. Third highest request.

And ideally, if you insist on using a phone for patch storage, include some wireless form of pairing.

I would like to see something for orchestral type sounds...strings, brass, choirs, maybe a pipe organ sample. And other samples like sax, flute, harmonica.

I would be in heaven if it also had mellotron samples for 3 violins, choir and flute.

I also really wonder what they were thinking when they put a toy piano in the CP, but not an acoustic sample.
I mean first off, if the reface line are more or less a celebration of past Yamaha products, I think Yamaha is far better known for acoustic pianos than toy pianos.
Second off, which sound would most people who would purchase a CP use more? I know that my need for a toy piano is somewhere below my need for the sound of 5 bagpipes through fuzzwah pedals, played by emus wearing lederhosen while standing on one foot atop a giant sea turtle.