Post halving i don't think there will be much interest for 16nm units anymore...
Keep in mind that almost 99% of miners consider the fiat profit as oppose of anything else, based on that, your statement may very well be inaccurate,notice how that as for right now,even mining with an old gear like S7 which is built on 28nm is in fact still profitable for 5 cents per kwh.
coin price is the number 1 decision maker in everything mining related, if after the halving and assuming difficulty increases by double, it only make sense that most 16nm gears will be paper weight but what if
BTC price is 50k by then ?
an S9 today makes about 5$ per day
after the halving (without taking price into calculation) S9 will make 2.5$
assuming diff will double s9 will make 1.25$ per day.
if price was to stay at 11,000$ per coin, that would be valid, but if say
BTC is at 50,000$ after the halving then S9 will make 5.6$ which is even a better profit than before the halving.
indeed non of the above is guaranteed to happen, but non of it is far from possible, diff doubling is very doable, coin price at 50k is very doable too.
The great thing about mining is that diff takes a lot of time to double, while price really takes no time when it wants to double, hint in 6 months we went from 3k to 14k = 328% increase to be accurate, while diff went from 5.6 to about 8 which is not even 100%.
