After the end of Ethereum mining, I will I think equally split my rigs between Ethereum Classic and ZCash. That is what most people will do I think
And thats the problem
After ETH ends, everything will end with it, there is no other altcoin that could support that much hashing power without killing profits in the process.
You know, we are definitely in a golden age, because back at the beggining of the year, mining was ten times less profitable, but yet still profitable ! So I believe we will simply get back to the mean. Also, AMD cards are bad at ZCash mining, so this will be left only for Nvidia cards, which are a lot less numerous.
If you compare vs MSRP, AMD cards are pretty close to NVidia on hash/$ for ZEC - and they're a tossup on hash/watt at any price.
They just don't ramp quite as high - yet - since AMD hasn't released new-gen "enthusiast" level cards yet, just mainstream ones.
Risk is growing pretty fast, with prices dropping on most or all of the "big cap" coins AND total hashrate still growing fast, while reward has dropped quite a bit just in the last week.
It's starting to look a bit iffy again on "will one achieve ROI if I build a new rig TODAY" for a lot of options - though if your electric cost is low, you should still manage ROI at some point.
If profitability drops back to where it was 6 months ago, I personally will be fine - I was plenty profitable THEN - but it would drive quite a few folks out of the mining business like the last "bust" did, at least for a while.
On the other hand, we might see another "price jump" stage too - no way to know for sure.