Yaaa me too. It's not about small trader. Low cost it's also means ETH scalability issue now becomes problem.
As you know ETH daily transaction only 2M transaction compared to BSC has 10M transaction per day
No it couldn't go up to 200M transactions per day, it was technically not feasible. What I am saying is that we will need at least 100M transactions per day and I think even moe than that if ETH is aiming at becoming the preferred network for developers to build applications for it.
Yaa i see your point. If ETH network can be upgraded to 100M transactions per day. It need more than ETH 2.0 maybe ETH 3.0 or 4.0

.
Just now ETH only can do transaction up to 2M per day and BCS up to 10M per day.
After ETH 2.0 launch we expect we can do transaction more than 10M per day.
Thinking about beacon chain, is it the same network like lightning network?
That's what it looks like and rolling out updates for large established networks is cumbersome as nothing must go wrong and you need all stakeholders on board. A lot of applications will be built for ETH and they all consume a piece of the transaction capacity. I don't know if sharding can do it. If I got it right there is also only so much that can be achieved with sharding. It's a rocky path to get there.