I think the low cost of the flea-scope justifies sticking to just one analog input per device, even with a successor, provided that the interface gets a little bit of an upgrade to be able to handle multiple scopes at once.
This would retain the small form factor and would keep the design free from compromises.
Wow, I love this idea -- I bet I could make an alternate UI display two analog waveforms from two devices instead of analog and digital from one... I don't think it would even require threading complexity, since the second device will only trigger after the first already has!
This would retain the small form factor and would keep the design free from compromises.