The Underwater Foot by Jon O'Kay

The underwater shot of the foot and the rest of Lost Island was brief but certainly as impactful as anything we've seen thus far in the parallel timeline. Why it's underwater?... is too early to speculate on that for me. I know that the so called incident was the big catalyst from where the timeline diverged. If the bomb went off the power of such a bomb was unlikely to submerge the island....why because the size of the bomb that Faraday carried was not big enough to do such a thing if such a bombf even exists. The energy escaping from the island and the power associated with that energy, on the other hand, is unknowably powerful potentially.

My theory then focuses on the fact that perhaps that is the end that MiB and Jacob are talking about. The destruction of the island and the ongoing quest to protect it and its unique qualities by Jacob is what he is hoping to achieve. The bomb would merely neutralized the energy exploding from the island. But if the bomb doesn't go off and the energy is allowed to be destroyed that would mean the end of that particular loop. However, the losties, or "candidates" as we now know them, somehow have escaped the end of this loop and "they're coming" to face off with MiB...that would explain his surprised look when Jacob reveals this to him. This is Jacob's progress he somehow extends the loop to continue on a little longer forcing MiB to continue his quest longer and stretching out the "ultimate conclusion" a little further out.