RE: Lost: Season 6 Episodes 1 & 2 - Spoilers for episodes 1&2
I believe that it will work, they'll get a ''reset'', but that's not due to the hydrogen bomb going off (for a H bomb to go off, the island wouldn't be under water, it'd explode in 47832934 pieces).
The H bomb exploding is what always happened. Something else will soon happen that'll change the course of history and therefore creating the ''alternate timeline'' which is basically the future.
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