Sounds good. Try a demo of the latest Cubase along with jbridge. An alternative to jbridge is something like 32bit bidule in rewire mode. Also, if Hypersonic can run in a stand alone mode, it’s possible to do that and route the MIDI and audio to/from Cubase using stuff like loopMIDI and ASIO Link Pro (both free). So…there are definitely ways to patch old plugins into the modern cutting edge versions of Cubase.
Unless you can find it still in stock at a reseller, or used somewhere, I’m not sure you can still get a 7.5 key for the dongle (but the software itself can still be downloaded from a Steinberg server). Any key newer than 7.5 will run it though. Cubase Pro keys can always ‘roll back’ to older/smaller versions.
You could buy the latest Cubase Pro @ Version 11. That key would let you run the latest as well as any version of Cubase that came before provided it’s compatible with the dongle/eLicenser system (also lower versions like Artist/Elements/LE/etc.).
If you did that, you could try something like jbridge with Cubase 11. Hypersonic should work out fine in such a bridge, just be aware that when importing old SX projects you might have to reconnect some things that’d be looking for the Hypersonic Plugin ID (rather than a bridge that is hosting it). My understanding is that most of your built in Steinberg effect plugins should find suitable replacements when importing projects into newer versions of Cubase (don’t be surprised if you have to manually sort some of those replacements on your own as well though).
I.E. If you try to load a project into Cubase and plugins or ports are missing, Cubase throws up options to connect to plugins and/or ports that DO exist on your installation.
So, you’d first get your bridged stuff working in fresh/empty modern projects…then with some luck the older stuff would be fairly easy to just ‘reconnect’ what is needed.
Also with luck, the 32bit version of Cubase 7.5 might just load your old SX projects right away and pick up where you left off. Maybe…
You could ALSO install 7.5 to give you the intermediary solution that might help when importing old projects that use a lot of third party 32bit plugins.
On ‘upgrading’ SX all the way to Cubase 11. SX goes way back…so I’m not sure if that dongle is compatible with the newest stuff? You could ask someone official at Steinberg. Personally, even if it’s compatible…due to the age of it, I’d probably keep your old SX dongle and license untouched, and start with a brand new key and dongle for version 11 rather than trying to ‘upgrade’ the SX key (probably would not be that much of a discount going that far back anyway).