Companies can profitably expand production at under $50 much faster today than 10 years ago due to the significantly expanded capital base, there are way more drilling rigs and trained crews, pumps, etc.  Declines have always been a factor and while shale wells decline significantly early on, they produce for much longer so once you have layered on years of shale production that has seen that big decline, you have a more stable decline curve and more production goes to growth rather than replacement.  That's what happened in natural gas.  And in addition to the restart of projects and new exploration activities, there are still numerous long-life projects that weren't shelved and haven't yet started producing.  

Demand growth will be temporary, we're getting closer to peak demand.  

Producers are hedging as their risk-appetite has changed and the futures curve is quickly flattening.  Floating storage will come back to land. Nothing supports $80 other than pipe dreams.