Neat proposal. It's worth mentioning that it can't be implemented in the current bitcoin implementation, yet the alpha sidechain introduced here happens to add exactly the bits it requires to work, namely time locked transactions and a more plausible malleability fix.
Which means if you find/build another altcoin with similar capabilities, you can start exchanging testnet coins with those altcoins using the very approach you describe today.
I don't believe that's a happy accident, but rather one of those core reasons for getting sidechains off the ground, as it provides a clear path toward finally building all the insane stuff people have been dreaming about for years.
It feels like there are much simpler ways to support pay on reveal secret directly on the bitcoin blockchain, if this is accepted as an important goal (e.g. with explicit conditional redemption conditions based on spending transaction blockcount).
But I guess a more general solution for time locking and malleability can give you other stuff as well (e.g. off chain payment microchannels).
Which means if you find/build another altcoin with similar capabilities, you can start exchanging testnet coins with those altcoins using the very approach you describe today.
I don't believe that's a happy accident, but rather one of those core reasons for getting sidechains off the ground, as it provides a clear path toward finally building all the insane stuff people have been dreaming about for years.