My concern is more about blockchain size than memory.

I know you are working to alleviate nodes RAM consumption. But having a small number of bots being able to stuff the blockchain of approximately 140MB in 10 hours, even if taken down by protocol is a problem for me. Such an attack, if repeated would generate 10GB of data in 1 month. That's the current size of the blockchain.

Being efficient at spamming is only a matter of how many accounts you have to perform it and we all know how easy it is to create fake accounts, especially if you have some mining power.

You may have read here that I added language detection to SteemSQL. This feature rely on a paid third party service, which fee is based on number of request and volume of data sent for language detection.
The spam attack made SteemSQL exhaust its quota and I had to upgrade it (pay more) to preserve this functionality. This is a direct impact of such an attack.

When you set up a new witness/seed node, you have to download and replay the whole blockchain which takes considerable amount of time. Even if you are working on faster replay, managing gigabytes of data has a cost.

I think this deserve an answer with more than ... "don't worry" (this is how I read your answer. I might be wrong)

Could you explain/describe wath mechanism is (or will be) put in place to prevent this to occurs again, even at a larger scale?