what happens as a result of the hard fork? will there be a chain split? Does PoS happen after Oct 17 or is that just the first phase?
The hard fork will not result in a chain split. This is going to be 4th time that ethereum going through hard fork but so far we only have eth and etc. The most likely hard fork that will result in a chain split that i guess will be the changing of POW to POS. A lot of money has been invested in getting gpu to mine eth. So by changing the POW to POS, this will make millions or even billions of dollar spent on equipment to become useless. So there will be a group that will want to split out to carry on the POW to justify their money earning equipment.
Ok, but I think this hard fork is to prepare for POS? I'm trying to find more information on it, and I think this article is helpful:
https://btcmanager.com/byzantine-first-part-of-ethereums-planned-hard-fork-activates-oct-17/so it looks like this hardfork will reduce block rewards and lay the way for eventual POS, which I think is coming pretty soon anyway, so it seems like there will be another chain split soon??
The GPUs can be re-purposed to mine for other coins IMHO. I have one GPU which I think I'll just re-purpose.