I don't know how many times we have to publicly say "VTC will hardfork if necessary to keep ASICs out" - we must have said it a hundred times!
I'll say it again, in case repetition number 101 will help - VTC will hardfork if that every becomes necessary to keep ASICs out. This isn't LTC, we're not going to suddenly decide to give up and capitulate in the face of a need to hardfork, we will do whatever is necessary to keep VTC decentralised and in part that means excluding ASICs by whatever means necessary.
2 questions:
1) What exactly is a "hard fork" and how does it prevent ASICs from adapting to the algorithm in-use.
A hard-fork usually refers to a software update that causes disagreement between the new version and older version as to what constitutes a valid block (like changing the proof of work algorithm would do). This will cause the old and new versions to be on different chains for future blocks, a fork in the chain (hence the hard-fork term). ASICs won't be able to adapt without redesigning the chip since they're highly specialised circuits (one of the reasons they're so much faster than GPU/CPUs is that they can cut away all the generalised stuff and use more die area for specialised computational logic). So many changes of the proof-of-work algorithm will make them useless for mining Vertcoin.
2) How can one tell exactly when ASICs have penetrated VTC mining, vs when GPU's shift to VTC mining because ASICs have forced them out of Scrypt?
This is purely hypothetical at this point, so let's consider Litecoin. You can't tell exactly, but you'll know when ASICs are starting to take over. If you compare the scrypt1024 asics to GPUs, e.g. the zeusminer 90mhash miner, that is ONE piece of hardware that equals ~
120 radeon 280x, at a fraction of the power usage.. those 280x would use like 32kW while the zeusminer will use what, 1.2kW? Since most large miners are limited by the amount of electricity their houses/facilities can provide, this means that they can replace all their gpus with asics and gain a ~27x increase in hashrate at the same power consumption. Now imagine if they all did that, I'm sure you can see how that will quickly push out anyone gpu mining. These numbers gets even worse when you consider the KNC Titan..