I expect the people that got ripped off for $2500 for what was widely criticised as a buggy version 1.0 are very pissed off now. I think a lot of bugs have come out of the hacking apart of AD. They still won't admit that one software with tiered licensing is the way to go but then they want to make sure people feel like the rejects they are until they stump up the cash for AD. Proteus is tiered and that works great for them.
That would depend on the software and the pricing tiers. In the lower-cost space it's hundreds and the business space it's expected to cost thousands.
It would be smart to have the same backend, but different branding and limited functionality. Remove the vault, simulators, limit the size so you can't do large backplanes, limit depth to 8-10 layers, maybe simplify the GUI some, etc etc. Convert files UP to the premium but limit conversions down.
Inexpensive CAD tools are great, but it just doesn't make business sense to cannibalize the primary product. The low-cost variant should be a lead-in and draw to the premium and not divert people away.