This is something I'm familiar with! I refined the above algorithm to reconcile statements according to the statement end balance. It works well, and yes it's knapsack.
You could and should discuss on the mailing lists. Agree scheduled transactions are not visible from bindings, and it could be a feature request. If you wanted to so depreciation of assets you could easily do your own calculations via scheme or python.
Huh there's a Balance Forecast report which does exactly this. It considers the Scheduled Transactions applicable to your accounts, and shows the forecasted balances.