Low level exhaust and equal size panniers option, preferably touring style panniers (to save me doing it again myself on my next bike!)
Joystick like that on latest Triumphs, to replace large, clumsy and badly placed wheel. Having stripped one of these down and seen how mechanically and electronically complex it is to achieve a relatively simple function, this design must be costing BMW a fortune. I'm sure a joystick would be much cheaper, less intrusive and more ergonomic.
Secondary TFT, mounted above instruments TFT, and supporting Android Auto and Apple CarPlay, plus powered compartment in fairing to hold the mobile phone required to drive this.
I think putting full map based nav, or mirroring phone screen, onto the current instruments TFT display is a non-starter, and in any case I think a satnav display needs to be higher up. A hybrid system attempting to use an app on your phone as the engine to power features on the TFT, is evidently not BMW's area of expertise, as can be seen from the current integration fiasco. All the stuff they are trying and failing to do reliably - like integrating telephony, music player and satnav, are all available and working on mobile phones already. Just give us a second touch sensitive screen and possibly a joystick to link to a phone, and via the phone's native capabilities and the thousands of existing apps, all those add-on features would be much more conveniently and reliably available, just as they are in many cars these days.
Built-in accessory power feeds - like those provided by HexEzcan. Why can't this be provided at the factory instead of having to strip down the bike to add additional power connections for things like dashcams, phone chargers, additional brake lights, etc.
To be honest I don't feel the need for more power, but a little less weight would be welcome.
Adjustable footrests, and corresponding gearshift and brake lever adjustment.
Dual Clutch Transmission option - the ultimate quickshifter!
Fred