well faster at low res would always be nice.

nozzles that just click in and out and are universally compatible. That would also be nice.

Printbite is good, but not everything sticks to it and not everything wants to let go either - but a universal print surface that every thing stuck to while printing and didn't stick to when printing had stopped.
I'd probably pay more for that than any other aspect of printing it's the single most frustrating thin about 3d printing.

Couple that with auto calibration that was fast and perfect and, i honestly don't think - as things stand - I'd want much else.

If you can print fast, with any material and it always sticks when needed and lets go when needed and it's never out of calibration - that's the holy grail really.

Now throw that lot at a bnc3d sigma dual independant extruder setup, but with direct drive not bowden (use flex3drive for lightweight directdrive setup) and you've got what I'd consider to be the perfect FDM printer.