Paradoxically, I think it will both decrease and increase simultaneously.

The Lightning L2 scales L1 by reducing but not eliminating its load, as L2 settles on L1.

L2 adds additional value to users by means of higher speed, lower cost, or other benefits.

Thus, offloading L1 to value-adding L2s may increase overall usage above what pure L1 would as it adds capabilities and use-cases, thus increasing the L1 usage and "security budget" further rather than the other way around. I don't think this is controversial.