There is an eip that will reduce a 4gb dag to 2.5gb making all 4gb and 3gb cards to work again, might help with the 51% attack as it will cost more to do a 51% attack but as the attack costs more the reward of doing it is also greater. So not sure if it really will help it.
I don't think it will be better for miners. As soon as 4GB video cards cannot mine ETH, they will increase the hashrate for ETC and kill the profit.
And statistics says that 48% of AMD video cards on the Hive pool have 4 GB of memory.
https://hiveos.farm/statistics_ruIt won't be better for miners for sure. Because their miner reward is just way too low. However many people who got free or very cheap power are going to mine it anyways. It will most likely be more profitable than EXPANSE is right now.
Look at how many people were still mining ETH when it was $80, there was still tons of hashrate on the network and most likely this will happen also to ETC after they lower the Epoch DAG.
This is actually pretty smart because the only other solution would of been to switch the algo but it would of been too difficult and ETC would definitely not be Ethereum Classic then.