What happens when BCH gets overloaded?

Lets say over the next year or so BCH picks up, starts getting thousands of transactions per second.

With 0-conf, these TXs can be practically accepted by a merchant at the moment they get into the mempool. But what if even though there are TXs being used floating in the mempool, they are not getting confirmed fast enough, and so they accumulate in the mempool. Think of a faucet whose spout spews faster than the drain and drain. So if the theoretical limit of the mempool is reached, if the water is overflowing, what happens?

If the mempool size is 300MB, for example, that's 1.2M transactions. This comes out to about 213 transactions per second.

I suppose my question is twofold.

With the current mempool limit and block size, BCH can definitely handle bursts of higher TPS, but what happens exactly if the average is above 213 TPS and is maintained for too long? Could "0-conf"'d transactions get dropped if this is sustained for long enough?

Also, assuming that if BCH does approach these limits, there would have to be a co-ordinated effort to increase block size and/or mempool size, how fast can this be "deployed" realistically? What would be the practical steps of such a thing? What would be involved?