If anyone can do it, I bet sidehack could figure out what would be the best way to encase a single blade, an issue would be controllers though if Bitmain isn't involved.
So is the S7 board size so different that it would not fit in an S5?
Maybe Bitmain could offer an upgrade package?
S7 board has heat sinks all over it.
S5 upgrade would be nice, but don't hold your breath (remember the story of S2 upgrades).