Question - How will base layer scale to 1,000 TPS?

I read the post about the merge not significantly reducing gas fees because the block time will go down from 13 sec. -> 12 sec. If that's true, how will the base layer scale to 1,000TPS if there will only be 1 execution shard? Won't it process the same number of transactions even if data shards are introduced? Thanks everyone.

Note: I thought I remember someone (possibly Vitalik) stating that the base layer will scale to 1,000 TPS (L2s scaling up to 100,000TPS) during a podcast. Maybe I'm misremembering, but I could've sworn that was the case.