There's a piece missing from Bakkt's model: what's their strategy for handling a run on BTC holdings? It's very tempting to assume that their deliberation on the subject concluded that it can only happen once, and to plan for that contingency appropriately. It's the same model as gold certificates after all; do or say anything and everything to play for as much time as you can get, then make sure you are well positioned when you default (hell, not even acknowledging the default is an option, "pivot to quantum currency" maybe? )
Another perspective would be this: if you had a choice between trading with Bakkt's model (multiple claims to the same underlying asset, but higher potential reward for higher potential risk), or using atomic swaps between cryptocurrencies, which would you choose? Both would potentially be very lucrative. And the answer has alot to do with guessing how long Bakkt might remain BTC-solvent.