To better illustrate idea: This will enable something like trust-less cross-chain Bitcoin ETF. On other chains will be traded permission to unlock bitcoin within a year (or customized period of time) . In case of ETF price increase, more people will be interested to lock their BTC and arbitrage price. In case of ETF price drop, there will be demand to burn side chain tokens and release BTC from script. Anyway it will create amazing financial product, stimulate on-chain activity and will create demand for block space and BTC itself.