I think it’s safe to say that validating the DAG and knowing which incoming TX to trust and which one not has been considered one of the greatest (if not the greatest) challenge when it comes to a DAG based native currency … considering TX cost and speed I think it’s safe to assume that the DAG might grow at least as fast as the ETH blockchain … will there be public validators or is everyone assumed/expected to download data ~size of ETH blockchain to make sure the incoming TXs are trustworthy …? if there are public validators what makes them trustworthy? … do we not need validators because nodes only accept TXs that are valid anyway? what do we do on data forks (I think it has been mentioned that they can exist even for e.g. graphEntry; they really appeared at one point in Beta too and it caused the faucet to fail iirc)? what do we do if someone managed to introduce a graphEntry that should not exist how do we get rid of that invalid branch again?
… more questions than answers for now I guess …
but I’m not the greatest blockchain/DAG expert - so 
ps: especially with TXs (creating a GraphEntry) just costing cents or maybe even less that raises the question how many hops are needed for validating 
… if put costs for 1000 hops are at 10 USD (I am not sure those numbers have anything to do with real graphEntry cost 
) that would require at least 10_000 checked hops for a incoming TX of value 100 USD … (and that assumes prices have never been lower … )