It would maintain an imperfect clustering, but still much better than current behavior.
I thought about that, too. The "imperfect clustering" made me erase everything I'd written. If the clustering is imperfect, it's not really clustering. It would mean less random reads to restart the seek chain though, so it would be a perceptible gain. But it's still not real clustering until the order is maintained indefinitely.
So far as I know, that simply can't be done with MVCC. Especially on an insert-only table that's clustered on a column unrelated to insert order.
How is this implemented in MS SQL then? Obviously, MS SQL supports real clustering and has MVCC..