My 4gbs still works on hiveos on eth so don't spread bullshit

ETC may stop in few hours when it reach DAG 380.

I think OP was referring to running in a Windows environment for his first mention of the rigs stopping. Linux will be able to continue on for a few more Epochs than Window due to less overhead loaded onto the card but that's only buying a few weeks. The end of the 4GB card is nigh. Raven is about to get a huge dump of cards unless ETC can implement their DAG update before then.

I'm still mining ETH on my 4gb cards with Team Red Miner. (Non monitor cards) -- In windows.

we are step closer to the end of eth mining journey, most 4gb cards wont mine etc again should increase profit for while
eth 2.0 on the horizon, buy on the dip while still have time to join pump show......hope 1337 bot show up again

Mining on windows with 4GB cards are no problem. Use the right driver and internal gpu as first gpu.

There is no exact day or week, much miner developers update there software to mine longer with 4gb cards, so mine as long as you can. With lolminer 1.11 you can mine on windows up to december 2020.

Very difficult to answer. I will restrict to AMD 4Gs. Also limiting it to full speed mining:

On most Linux systems the last epoch is 381, some do 382, but that is rare. Some very rare cases are 380, but that is an old driver then.
Overall to get to 381 use a recently released miner that still gets updates and is tested for that. Often it will need a split DAG file (but e.g. Claymore still uses a single big DAG ... that may end earlier)
Epoch 381 by the way will last from Dec 15th to Dec 21st.

On Windows the thing is more problematic. Allocating the max avail memory there is hard to achieve at all and if then with some very dirty techniques. That said: What works on system A may fail on B and vise versa.
Overall realistically 374/375 can be done. I did benchmark my miner on 376 on my system, but that might fail on any other. Also here: use recent releases!

Now the thing with reduced mining speed:
There were recent releases of miners that allow to continue mining on 4G card at slowing down speed. See here: https://medium.com/p/ea8f6298f813
Given that technique the speed will go down over time, but actually the card will not really stop to mine until you stop it (or your OC settings stop you, because this modes need a bit more juice / relaxed uv). But that way you are able to go on some epochs until you find it unprofitable.
Here an example for a normally 30mh/s card using this:


So well ... making long story short: It depends!

Yes I didn't think this was possible but its actually pretty smart what they did. They are going to get great dev mining fees as a result of this since many of the 4GB cards will have no choice but to switch to lolminer. According to some statistics its estimated that around 50% of the entire network hashrate is still on 4GB GPUs. So assuming the 4GB ASICs are nil, then there is going to be tons of hashrate that will move to this miner.

Eventually later in the new year it won't make sense to mine with 4GB even with lolminer but for the first few DAGs the speed slowdown is not that drastic. I don't think ETC is going to be profitable at all. Most likely all the ETH ASICs will move to ETC as soon as they can't mine ETH anymore sometime in the next month or so.