You really are an opinionated nicompoop.
And that makes you what?
What makes you believe that we are all in this to fall within the constraints of your nifty little spreadsheet on whether we'll make returns and by when? And just in case you missed it, bitmain are actually considering an S1 to S5 kit, so there!
As dogie said, they can consider, just as I consider doing a lot of things that I never end up doing. I'm not saying they won't do it either, they'll certainly do it if they feel there are enough "nincompoops" around who will fall for the illusion of saving money by doing an upgrade. I'm just throwing out my advice to help guide anyone who may fall victim to the illusion of saving a few dollars. It is a tempting siren song, after all. Don't feel bad if you were tempted and have now come to your senses, it is completely understandable.