1) No, but with sharding it could happen. Sharding is a scalability solution being pushed for. Wouldn’t be failure it would miss some information. An application not designed for this missing information could break irrecoverable. Its a data availability issue.
2) Most of today’s largest blockchains can handle VISA levels of transactions and the bandwidth has been used for something like NASDAQ levels of transactions (but doesn't reach that) since its mostly trading of assets on those blockchains. (The “merchant adoption” use case was always a small use case being masqueraded as a “killer app”by irrelevant people grasping for any use case, but its worked to get more relevant interest into the system, so maybe you heard that, the VISA benchmark is still useful though) When a form of sharding is implemented they get an additional 1-2 orders of magnitude more bandwidth. We’ll see how it pans out.
2) Most of today’s largest blockchains can handle VISA levels of transactions and the bandwidth has been used for something like NASDAQ levels of transactions (but doesn't reach that) since its mostly trading of assets on those blockchains. (The “merchant adoption” use case was always a small use case being masqueraded as a “killer app”by irrelevant people grasping for any use case, but its worked to get more relevant interest into the system, so maybe you heard that, the VISA benchmark is still useful though) When a form of sharding is implemented they get an additional 1-2 orders of magnitude more bandwidth. We’ll see how it pans out.