Im somewhat screwing myself on my electric bill right now with 2 of my miners being S7s. I could replace them with 1 S9 and have more hash with less power consumption. S7 just arent worth anything anymore for me to even feel like dealing with getting rid of them.
I have a storage locker with a bunch of outdated and inefficient miners (M3s, S7s, A742, etc) - if prices do go crazy again, they'll be sellable.
Not a bad plan. I may copy that.