[DennisP]

Yes and the point there isn't so much that on-chain transactions are "supposed to be expensive," but that zkrollups are just as secure as on-chain transactions but scale an order of magnitude better than executable shards, so executable shards start to look a little superfluous.

The researchers have floated the possibility of incorporating zkrollup tech into L1 eventually, but with the tech advancing so quickly it's hard to say whether it will ultimately make sense.