I have to admit, that I find 8-steps always too limited. The least
minimal phrase I can stand with is a 4/4 bar with 16th notes, vulgo a
16step sequencer (more would be better).

I could imagine a modular sequencer, which consists of an adress
generator (like the A154), and various chainable module. E.g two 8-step
modules which can be played either A-B or A-A-A-B.
Also there could be
several kinds of modules like switches for gate/trigger, potentiometers
for non tonal cv, 12position switches for tonal cv's. etc pp.

Florian