That is a great write-up. I could not find any issues with this construction.
This “more viable plasma” will not just make token-transfers of a plasma chain much easier, but getting rid of confirm transactions will also benefit many other applications of the plasma-technology.
E.g. plasma exchanges had always the problem that not the order taker, but the order placer had a “free option” to cancel the trade right after the trade was executed. This free option was needed, since during the trade a data unavailability could happen.
With this construction it should be able to allow people match an order from a orderbook with a transaction output older than the order transaction. Then, the trade can be settled with a priority of the youngest trade input. This would have the effect that the order placer knows that the priority of the trade is high enough to exit before any malicious behavior occurred and thereby we do not have to give him the “free option” to cancel the trade.
I really really like this construction of the more viable plasma!