IMO you could do a no frills Catalyst pedal (ok, maybe add 1-2 of the most loved additional models). Alternatively, let the user add 2-3 models pre-selected in the editor. The rest could be pretty much Boss-alike, as in exposing the most relevant parameters with anything advanced requiring the editor.
All that would be pretty much like an Amplifirebox on stereoids, a concept I personally really like, especially in case you could use it straight from the start without ever even connecting the device to your computer.
Anyhow, as long as I can see so far, if you were to come out with such a box, you'd blow the competition away because of the sound quality. Maybe the IR-2 needs some more tweaking, no idea, but from all I heard so far, it doesn't hold a candle against the Line 6 amps - which actually is a pity, as otherwise it'd be a pretty instant buy.