We just figured out that we can actually use Liquid script to do custom HTML / videos / logic to upsell people with videos and all that jazz. We really wish we had known that, because it could've meant hundreds of thousands in business for us a year...
In any case, we still would like to see improved upsells / downsells. We can do basic stuff using Liquid script, but what about this:
Contact buys X -> Offer Y. If they take Y, go to course. If they don't take Y, offer them Z.
This would be super helpful for us. Hope you can build it.