You owe $100k, but you also have something of value (worth approximately $100k when the lease was entered, but should be adjusted for transaction costs of subleasing). Over time, your payments reduce the debt (this balances out), but the asset also reduces value, which reduces your overall balance. Adjustments for marketability of the leased property should also be made.

If the property isn't marketable, maybe the current asset value is $0, but that's rarely the case.