Dust protection

Why Dust attacking is an issue to IOTA is because the tangle has only one ledger. With sharding, the tangle can have ledger for every shardings.
If the tangle has one million shardings, dust attacking won’t be an issue anymore.
What we can do is giving a size limitation for a ledger of sharding,
if a ledger is larger then a setting parameter, a sharding will spit into at least two automatically.
When dust attacking attacks on a sharding, the ledger would expend and finally spit into two. Because size of a ledger is limited dust attacking won’t damage the tangle

That could be a dust protection solution.
And b4 Coordicide, dust burning solution still can be used.

Fundamentally you are correct, but as with sharding, you do need some sort of protection, otherwise an attacker can go through and fill each shard’s db.

But you are right that a sharding solution should take these types of ideas in mind.

If attacker would fill each shard, each shard would spit. The only problem would be the tangle has too many shards

Each time the shard splits, the security is reduced. So a shard can only split if there is a enough honest nodes monitoring it.

Also need some mechanise to re-join separated shards back to one