You asked the same thing over two years ago and never got a response. What makes you think the result will be any different this time?
https://forum.synapse-audio.com/viewtopic.php?f=5&t=13004&p=119800#p119800It's not just VST 3 support, people will then want a resizable GUI so they can use it on modern resolutions, then they'll expect a preset browser, then they'll want Mac M1/ M2 support and it would have to be updated every time Apple changes a line of code in their OS and so on.
All that just to end up with a product that would compete for sales with their flagship synth DUNE 3.
I've seen maybe three or four people ask for DUNE 1 back so if you think it through it really makes no sense for Synapse to put in all that time and effort. It would make much more sense for them to put that time and effort in to DUNE 3 or new products.
I think you can still get Dune CM 64 bit from Computer Music magazine and if your DAW doesn't support VST2 then you need to contact them. Isn't there a VST2 to VST3 wrapper for Cubase users?