If you run a node on lightning, you would know how much transactions you've forwarded, so you can make estimates, especially if you run a large node (say Bitfinex that runs their own nodes), but lightning isn't public the same way blockchain is.

The 1MB block limit makes it highly likely that there will be transactions in the mempool, you still need to open/close channels (even batched ones) and presumably large transfers for cold storage still happen on the blockchain, but then again it's very difficult to say what happens in year ~2140, we'll all be long gone by then.