Just to use EPD as an example of how cheap NS is for a potential acquirer --
If EPD offered $60/shr and paid for it entirely in new EPD units, they would have to issue 69 million new units. That would cost them $180 million in new distributions, which is savings of $80 million less than what NS is currently paying. They'd probably mix new units with new debt, maybe 1:1, so they'd be retiring some NS units at low-rate debt + replacing NS debt with lower-rate debt, while getting rid of NS mgmt and saving even more money.
Some of these bigger MLPs have to be looking at NS at these prices. NS is running $260 million in distributions + $100 million in interest, EPD would probably cut that in half (or more) easily off the same assets, that could add an immediate 15-20 cents per share to EPD distribution.
NS shareholders would see income drop to equivalent of $3./unit, but would you really turn that down at this point if you got a pop to $60 in the unit price??