It's something everyone can see coming, meaning rational people will adapt slowly before it hits.
Price may rise, difficultly might go down, more efficient/cheaper hardware is being developed.
So is it a bad time to buy old hardware? Do you think the value of S3's for example are about to plummet?
S3's are getting very old. If your electricity is free or very cheap, anything can be good though. I still mine with my S1.
Thanks, do you think if I buy some used S3s right now they will last for another year or two? Will they still be worth anything?
Nobody can tell for sure, mining difficulty is speculative.
The problem with miners like S3s and S1s is that it's really hard to absorb the shipping cost when it's time to resell.
I definitely wouldn't go over a year for a S3.