This is indeed the optimal strategy for miners - to drop rollup transactions in favor of more execution-oriented transactions. Isn’t there a risk that it’ll actually hurt rollups?
At high congestion times (e.g. big NFT sales) rollup transactions will be constantly dropped, and they’ll have to compensate for the lack of execution gas by paying a higher total fee. Theoretically it should drive rollup gas fees to the current cost, except that it also limits the calldata size. The additional constraint might require them to pay an even higher fee to outbid other rollups competing on the same calldata space.